I am using Ubuntu 14.04 LTS x64. I did a sudo apt-get upgrade yesterday and restarted my PC. Now my taskbar and panel are missing. When I try to restart Unity using unity --replace Then I get error:

unity-panel-service stop/waiting
compiz (core) - Info: Loading plugin: core
compiz (core) - Info: Starting plugin: core
unity-panel-service start/running, process 3906
compiz (core) - Info: Loading plugin: ccp
compiz (core) - Info: Starting plugin: ccp
compizconfig - Info: Backend     : gsettings
compizconfig - Info: Integration : true
compizconfig - Info: Profile     : unity
compiz (core) - Info: Loading plugin: composite
compiz (core) - Info: Starting plugin: composite
compiz (core) - Info: Loading plugin: opengl
compiz (core) - Info: Unity is fully supported by your hardware.
compiz (core) - Info: Unity is fully supported by your hardware.
compiz (core) - Info: Starting plugin: opengl
libGL error: dlopen /usr/lib/x86_64-linux-gnu/dri/i965_dri.so failed (/usr/lib/x86_64-linux-gnu/dri/i965_dri.so: undefined symbol: _glapi_tls_Dispatch)
libGL error: dlopen ${ORIGIN}/dri/i965_dri.so failed (${ORIGIN}/dri/i965_dri.so: cannot open shared object file: No such file or directory)
libGL error: dlopen /usr/lib/dri/i965_dri.so failed (/usr/lib/dri/i965_dri.so: cannot open shared object file: No such file or directory)
libGL error: unable to load driver: i965_dri.so
libGL error: driver pointer missing
libGL error: failed to load driver: i965
libGL error: dlopen /usr/lib/x86_64-linux-gnu/dri/swrast_dri.so failed (/usr/lib/x86_64-linux-gnu/dri/swrast_dri.so: undefined symbol: _glapi_tls_Dispatch)
libGL error: dlopen ${ORIGIN}/dri/swrast_dri.so failed (${ORIGIN}/dri/swrast_dri.so: cannot open shared object file: No such file or directory)
libGL error: dlopen /usr/lib/dri/swrast_dri.so failed (/usr/lib/dri/swrast_dri.so: cannot open shared object file: No such file or directory)
libGL error: unable to load driver: swrast_dri.so
libGL error: failed to load driver: swrast
compiz (core) - Info: Loading plugin: compiztoolbox
compiz (core) - Info: Starting plugin: compiztoolbox
compiz (core) - Info: Loading plugin: decor
compiz (core) - Info: Starting plugin: decor
compiz (core) - Info: Loading plugin: vpswitch
compiz (core) - Info: Starting plugin: vpswitch
compiz (core) - Info: Loading plugin: snap
compiz (core) - Info: Starting plugin: snap
compiz (core) - Info: Loading plugin: mousepoll
compiz (core) - Info: Starting plugin: mousepoll
compiz (core) - Info: Loading plugin: resize
compiz (core) - Info: Starting plugin: resize
compiz (core) - Info: Loading plugin: place
compiz (core) - Info: Starting plugin: place
compiz (core) - Info: Loading plugin: move
compiz (core) - Info: Starting plugin: move
compiz (core) - Info: Loading plugin: wall
compiz (core) - Info: Starting plugin: wall
compiz (core) - Info: Loading plugin: grid
compiz (core) - Info: Starting plugin: grid
compiz (core) - Info: Loading plugin: regex
compiz (core) - Info: Starting plugin: regex
compiz (core) - Info: Loading plugin: imgpng
compiz (core) - Info: Starting plugin: imgpng
compiz (core) - Info: Loading plugin: session
compiz (core) - Info: Starting plugin: session
I/O warning : failed to load external entity "/home/sumeet/.compiz/session/10de541a813cc1a8fc140170575114755000000020350005"
compiz (core) - Info: Loading plugin: gnomecompat
compiz (core) - Info: Starting plugin: gnomecompat
compiz (core) - Info: Loading plugin: animation
compiz (core) - Info: Starting plugin: animation
compiz (core) - Info: Loading plugin: fade
compiz (core) - Info: Starting plugin: fade
compiz (core) - Info: Loading plugin: unitymtgrabhandles
compiz (core) - Info: Starting plugin: unitymtgrabhandles
compiz (core) - Info: Loading plugin: workarounds
compiz (core) - Info: Starting plugin: workarounds
compiz (core) - Info: Loading plugin: scale
compiz (core) - Info: Starting plugin: scale
compiz (core) - Info: Loading plugin: expo
compiz (core) - Info: Starting plugin: expo
compiz (core) - Info: Loading plugin: ezoom
compiz (core) - Info: Starting plugin: ezoom
compiz (core) - Info: Loading plugin: unityshell
compiz (core) - Info: Starting plugin: unityshell
WARN  2014-06-02 18:46:23 unity.glib.dbus.server GLibDBusServer.cpp:579 Can't register object 'org.gnome.Shell' yet as we don't have a connection, waiting for it...
ERROR 2014-06-02 18:46:23 unity.debug.interface DebugDBusInterface.cpp:216 Unable to load entry point in libxpathselect: libxpathselect.so.1.4: cannot open shared object file: No such file or directory
compiz (unityshell) - Error: GL_ARB_vertex_buffer_object not supported

ERROR 2014-06-02 18:46:23 unity.shell.compiz unityshell.cpp:3850 Impossible to delete the unity locked stamp file
compiz (core) - Error: Plugin initScreen failed: unityshell
compiz (core) - Error: Failed to start plugin: unityshell
compiz (core) - Info: Unloading plugin: unityshell
X Error of failed request:  BadWindow (invalid Window parameter)
  Major opcode of failed request:  3 (X_GetWindowAttributes)
  Resource id in failed request:  0x3e000c9
  Serial number of failed request:  10115
  Current serial number in output stream:  10116

Any help would be highly appreciated.

EDIT : My PC configuration

    description: Portable Computer
    product: Dell System XPS L502X (System SKUNumber)
    vendor: Dell Inc.
    version: 0.1
    serial: 1006ZP1
    width: 64 bits
    capabilities: smbios-2.6 dmi-2.6 vsyscall32
    configuration: administrator_password=unknown boot=normal chassis=portable family=HuronRiver System frontpanel_password=unknown keyboard_password=unknown power-on_password=unknown sku=System SKUNumber uuid=44454C4C-3000-1030-8036-B1C04F5A5031
*-core
   description: Motherboard
   product: 0YR8NN
   vendor: Dell Inc.
   physical id: 0
   version: A00
   serial: .1006ZP1.CN4864314C0560.
   slot: Part Component
*-firmware
      description: BIOS
      vendor: Dell Inc.
      physical id: 0
      version: A11
      date: 05/29/2012
      size: 128KiB
      capacity: 2496KiB
      capabilities: pci pnp upgrade shadowing escd cdboot bootselect socketedrom edd int13floppy360 int13floppy1200 int13floppy720 int5printscreen int9keyboard int14serial int17printer int10video acpi usb ls120boot smartbattery biosbootspecification netboot
 *-cpu
      description: CPU
      product: Intel(R) Core(TM) i7-2630QM CPU @ 2.00GHz
      vendor: Intel Corp.
      physical id: 19
      bus info: cpu@0
      version: Intel(R) Core(TM) i7-2630QM CPU @ 2.00GHz
      serial: Not Supported by CPU
      slot: CPU
      size: 800MHz
      capacity: 800MHz
      width: 64 bits
      clock: 100MHz
      capabilities: x86-64 fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp constant_tsc arch_perfmon pebs bts nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx lahf_lm ida arat epb xsaveopt pln pts dtherm tpr_shadow vnmi flexpriority ept vpid cpufreq
      configuration: cores=4 enabledcores=4 threads=8
    *-cache:0
         description: L1 cache
         physical id: 1a
         slot: L1-Cache
         size: 64KiB
         capacity: 64KiB
         capabilities: synchronous internal write-through data
    *-cache:1
         description: L2 cache
         physical id: 1b
         slot: L2-Cache
         size: 256KiB
         capacity: 256KiB
         capabilities: synchronous internal write-through data
    *-cache:2
         description: L3 cache
         physical id: 1c
         slot: L3-Cache
         size: 6MiB
         capacity: 6MiB
         capabilities: synchronous internal write-back unified
 *-memory
      description: System Memory
      physical id: 1d
      slot: System board or motherboard
      size: 6GiB
    *-bank:0
         description: SODIMM DDR3 Synchronous 1333 MHz (0.8 ns)
         product: M471B5273DH0-CH9
         vendor: Samsung
         physical id: 0
         serial: 450F1160
         slot: ChannelA-DIMM0
         size: 4GiB
         width: 64 bits
         clock: 1333MHz (0.8ns)
    *-bank:1
         description: SODIMM DDR3 Synchronous 1333 MHz (0.8 ns)
         product: HMT325S6BFR8C-H9
         vendor: Hynix/Hyundai
         physical id: 1
         serial: 0CA0E8E2
         slot: ChannelB-DIMM0
         size: 2GiB
         width: 64 bits
         clock: 1333MHz (0.8ns)
 *-pci
      description: Host bridge
      product: 2nd Generation Core Processor Family DRAM Controller
      vendor: Intel Corporation
      physical id: 100
      bus info: pci@0000:00:00.0
      version: 09
      width: 32 bits
      clock: 33MHz
    *-pci:0
         description: PCI bridge
         product: Xeon E3-1200/2nd Generation Core Processor Family PCI Express Root Port
         vendor: Intel Corporation
         physical id: 1
         bus info: pci@0000:00:01.0
         version: 09
         width: 32 bits
         clock: 33MHz
         capabilities: pci pm msi pciexpress normal_decode bus_master cap_list
         configuration: driver=pcieport
         resources: irq:40 ioport:3000(size=4096) memory:f0000000-f10fffff ioport:c0000000(size=301989888)
       *-generic UNCLAIMED
            description: Unassigned class
            product: Illegal Vendor ID
            vendor: Illegal Vendor ID
            physical id: 0
            bus info: pci@0000:01:00.0
            version: ff
            width: 32 bits
            clock: 66MHz
            capabilities: bus_master vga_palette cap_list
            configuration: latency=255 maxlatency=255 mingnt=255
            resources: memory:f0000000-f0ffffff memory:c0000000-cfffffff memory:d0000000-d1ffffff ioport:3000(size=128) memory:f1000000-f107ffff
    *-display
         description: VGA compatible controller
         product: 2nd Generation Core Processor Family Integrated Graphics Controller
         vendor: Intel Corporation
         physical id: 2
         bus info: pci@0000:00:02.0
         version: 09
         width: 64 bits
         clock: 33MHz
         capabilities: msi pm vga_controller bus_master cap_list rom
         configuration: driver=i915 latency=0
         resources: irq:52 memory:f1400000-f17fffff memory:e0000000-efffffff ioport:4000(size=64)
    *-communication
         description: Communication controller
         product: 6 Series/C200 Series Chipset Family MEI Controller #1
         vendor: Intel Corporation
         physical id: 16
         bus info: pci@0000:00:16.0
         version: 04
         width: 64 bits
         clock: 33MHz
         capabilities: pm msi bus_master cap_list
         configuration: driver=mei_me latency=0
         resources: irq:50 memory:f1c05000-f1c0500f
    *-usb:0
         description: USB controller
         product: 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #2
         vendor: Intel Corporation
         physical id: 1a
         bus info: pci@0000:00:1a.0
         version: 05
         width: 32 bits
         clock: 33MHz
         capabilities: pm debug ehci bus_master cap_list
         configuration: driver=ehci-pci latency=0
         resources: irq:16 memory:f1c09000-f1c093ff
    *-multimedia
         description: Audio device
         product: 6 Series/C200 Series Chipset Family High Definition Audio Controller
         vendor: Intel Corporation
         physical id: 1b
         bus info: pci@0000:00:1b.0
         version: 05
         width: 64 bits
         clock: 33MHz
         capabilities: pm msi pciexpress bus_master cap_list
         configuration: driver=snd_hda_intel latency=0
         resources: irq:53 memory:f1c00000-f1c03fff
    *-pci:1
         description: PCI bridge
         product: 6 Series/C200 Series Chipset Family PCI Express Root Port 1
         vendor: Intel Corporation
         physical id: 1c
         bus info: pci@0000:00:1c.0
         version: b5
         width: 32 bits
         clock: 33MHz
         capabilities: pci pciexpress msi pm normal_decode cap_list
         configuration: driver=pcieport
         resources: irq:16
    *-pci:2
         description: PCI bridge
         product: 6 Series/C200 Series Chipset Family PCI Express Root Port 2
         vendor: Intel Corporation
         physical id: 1c.1
         bus info: pci@0000:00:1c.1
         version: b5
         width: 32 bits
         clock: 33MHz
         capabilities: pci pciexpress msi pm normal_decode bus_master cap_list
         configuration: driver=pcieport
         resources: irq:17 memory:f1b00000-f1bfffff
       *-network
            description: Wireless interface
            product: Centrino Wireless-N 1030 [Rainbow Peak]
            vendor: Intel Corporation
            physical id: 0
            bus info: pci@0000:03:00.0
            logical name: mon.wlan0
            version: 34
            serial: bc:77:37:14:47:e5
            width: 64 bits
            clock: 33MHz
            capabilities: pm msi pciexpress bus_master cap_list logical wireless ethernet physical
            configuration: broadcast=yes driver=iwlwifi driverversion=3.13.0-27-generic firmware=18.168.6.1 latency=0 link=no multicast=yes wireless=IEEE 802.11bgn
            resources: irq:51 memory:f1b00000-f1b01fff
    *-pci:3
         description: PCI bridge
         product: 6 Series/C200 Series Chipset Family PCI Express Root Port 4
         vendor: Intel Corporation
         physical id: 1c.3
         bus info: pci@0000:00:1c.3
         version: b5
         width: 32 bits
         clock: 33MHz
         capabilities: pci pciexpress msi pm normal_decode bus_master cap_list
         configuration: driver=pcieport
         resources: irq:19 memory:f1a00000-f1afffff
       *-usb
            description: USB controller
            product: uPD720200 USB 3.0 Host Controller
            vendor: NEC Corporation
            physical id: 0
            bus info: pci@0000:04:00.0
            version: 04
            width: 64 bits
            clock: 33MHz
            capabilities: pm msi msix pciexpress xhci bus_master cap_list
            configuration: driver=xhci_hcd latency=0
            resources: irq:19 memory:f1a00000-f1a01fff
    *-pci:4
         description: PCI bridge
         product: 6 Series/C200 Series Chipset Family PCI Express Root Port 5
         vendor: Intel Corporation
         physical id: 1c.4
         bus info: pci@0000:00:1c.4
         version: b5
         width: 32 bits
         clock: 33MHz
         capabilities: pci pciexpress msi pm normal_decode bus_master cap_list
         configuration: driver=pcieport
         resources: irq:16 memory:f1900000-f19fffff
    *-pci:5
         description: PCI bridge
         product: 6 Series/C200 Series Chipset Family PCI Express Root Port 6
         vendor: Intel Corporation
         physical id: 1c.5
         bus info: pci@0000:00:1c.5
         version: b5
         width: 32 bits
         clock: 33MHz
         capabilities: pci pciexpress msi pm normal_decode bus_master cap_list
         configuration: driver=pcieport
         resources: irq:17 ioport:2000(size=4096) ioport:f1800000(size=1048576)
       *-network
            description: Ethernet interface
            product: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
            vendor: Realtek Semiconductor Co., Ltd.
            physical id: 0
            bus info: pci@0000:06:00.0
            logical name: eth0
            version: 06
            serial: 14:fe:b5:a3:ac:40
            size: 1Gbit/s
            capacity: 1Gbit/s
            width: 64 bits
            clock: 33MHz
            capabilities: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation
            configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=full firmware=rtl_nic/rtl8168e-2.fw ip=172.19.167.151 latency=0 link=yes multicast=yes port=MII speed=1Gbit/s
            resources: irq:49 ioport:2000(size=256) memory:f1804000-f1804fff memory:f1800000-f1803fff
    *-usb:1
         description: USB controller
         product: 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #1
         vendor: Intel Corporation
         physical id: 1d
         bus info: pci@0000:00:1d.0
         version: 05
         width: 32 bits
         clock: 33MHz
         capabilities: pm debug ehci bus_master cap_list
         configuration: driver=ehci-pci latency=0
         resources: irq:23 memory:f1c08000-f1c083ff
    *-isa
         description: ISA bridge
         product: HM67 Express Chipset Family LPC Controller
         vendor: Intel Corporation
         physical id: 1f
         bus info: pci@0000:00:1f.0
         version: 05
         width: 32 bits
         clock: 33MHz
         capabilities: isa bus_master cap_list
         configuration: driver=lpc_ich latency=0
         resources: irq:0
    *-ide:0
         description: IDE interface
         product: 6 Series/C200 Series Chipset Family 4 port SATA IDE Controller
         vendor: Intel Corporation
         physical id: 1f.2
         bus info: pci@0000:00:1f.2
         version: 05
         width: 32 bits
         clock: 66MHz
         capabilities: ide pm bus_master cap_list
         configuration: driver=ata_piix latency=0
         resources: irq:19 ioport:40b8(size=8) ioport:40cc(size=4) ioport:40b0(size=8) ioport:40c8(size=4) ioport:4090(size=16) ioport:4080(size=16)
    *-serial UNCLAIMED
         description: SMBus
         product: 6 Series/C200 Series Chipset Family SMBus Controller
         vendor: Intel Corporation
         physical id: 1f.3
         bus info: pci@0000:00:1f.3
         version: 05
         width: 64 bits
         clock: 33MHz
         configuration: latency=0
         resources: memory:f1c04000-f1c040ff ioport:efa0(size=32)
    *-ide:1
         description: IDE interface
         product: 6 Series/C200 Series Chipset Family 2 port SATA IDE Controller
         vendor: Intel Corporation
         physical id: 1f.5
         bus info: pci@0000:00:1f.5
         version: 05
         width: 32 bits
         clock: 66MHz
         capabilities: ide pm bus_master cap_list
         configuration: driver=ata_piix latency=0
         resources: irq:19 ioport:40a8(size=8) ioport:40c4(size=4) ioport:40a0(size=8) ioport:40c0(size=4) ioport:4070(size=16) ioport:4060(size=16)
 *-scsi:0
      physical id: 1
      logical name: scsi0
      capabilities: emulated
    *-disk
         description: ATA Disk
         product: SAMSUNG HN-M640M
         physical id: 0.0.0
         bus info: scsi@0:0.0.0
         logical name: /dev/sda
         version: 2AR1
         serial: S2T3J1KBC00006
         size: 596GiB (640GB)
         capabilities: partitioned partitioned:dos
         configuration: ansiversion=5 sectorsize=512 signature=6b746d91
       *-volume:0
            description: Windows NTFS volume
            physical id: 1
            bus info: scsi@0:0.0.0,1
            logical name: /dev/sda1
            version: 3.1
            serial: 0272-3e7f
            size: 348MiB
            capacity: 350MiB
            capabilities: primary bootable ntfs initialized
            configuration: clustersize=4096 created=2013-09-18 12:20:45 filesystem=ntfs label=System Reserved modified_by_chkdsk=true mounted_on_nt4=true resize_log_file=true state=dirty upgrade_on_mount=true
       *-volume:1
            description: Extended partition
            physical id: 2
            bus info: scsi@0:0.0.0,2
            logical name: /dev/sda2
            size: 116GiB
            capacity: 116GiB
            capabilities: primary extended partitioned partitioned:extended
          *-logicalvolume:0
               description: Linux swap / Solaris partition
               physical id: 5
               logical name: /dev/sda5
               capacity: 6037MiB
               capabilities: nofs
          *-logicalvolume:1
               description: Linux filesystem partition
               physical id: 6
               logical name: /dev/sda6
               logical name: /
               capacity: 110GiB
               configuration: mount.fstype=ext4 mount.options=rw,relatime,errors=remount-ro,data=ordered state=mounted
       *-volume:2
            description: Windows NTFS volume
            physical id: 3
            bus info: scsi@0:0.0.0,3
            logical name: /dev/sda3
            logical name: /media/os
            version: 3.1
            serial: 4e7853ec-5555-a74d-82e0-9f49798d3772
            size: 156GiB
            capacity: 156GiB
            capabilities: primary ntfs initialized
            configuration: clustersize=4096 created=2013-09-19 09:19:00 filesystem=ntfs label=OS mount.fstype=fuseblk mount.options=ro,nosuid,nodev,relatime,user_id=0,group_id=0,allow_other,blksize=4096 state=mounted
       *-volume:3
            description: Windows NTFS volume
            physical id: 4
            bus info: scsi@0:0.0.0,4
            logical name: /dev/sda4
            logical name: /media/data
            version: 3.1
            serial: 7666d55f-e1bf-e645-9791-2a1a31b24b9a
            size: 322GiB
            capacity: 322GiB
            capabilities: primary ntfs initialized
            configuration: clustersize=4096 created=2013-09-17 23:27:01 filesystem=ntfs label=Data modified_by_chkdsk=true mount.fstype=fuseblk mount.options=rw,nosuid,nodev,relatime,user_id=0,group_id=0,allow_other,blksize=4096 mounted_on_nt4=true resize_log_file=true state=mounted upgrade_on_mount=true
 *-scsi:1
      physical id: 2
      logical name: scsi1
      capabilities: emulated
    *-cdrom
         description: DVD-RAM writer
         product: DVD+-RW GT32N
         vendor: HL-DT-ST
         physical id: 0.0.0
         bus info: scsi@1:0.0.0
         logical name: /dev/cdrom
         logical name: /dev/sr0
         version: A201
         capabilities: removable audio cd-r cd-rw dvd dvd-r dvd-ram
         configuration: ansiversion=5 status=nodisc
*-battery
   product: DELL
   vendor: SANYO
   physical id: 1
   version: 2008
   serial: 1.0
   slot: Rear
   capacity: 57720mWh
   configuration: voltage=11.1V

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