i'm experiencing a strange problem with dual monitors. when i set the dual monitor via "nvidia settings" and save the setting to xorg.conf, the default unity theme and icons are turning back to gtk default. i also get an error telling me "could not apply the stored configuration for monitors"

here is my xorg.conf:

# nvidia-settings: X configuration file generated by nvidia-settings
# nvidia-settings:  version 280.13  (buildd@yellow)  Fri Aug  5 12:31:28 UTC 2011

Section "ServerLayout"
    Identifier     "Layout0"
    Screen      0  "Screen0" 0 0
    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"
    Option         "Xinerama" "0"
EndSection

Section "Files"
EndSection

Section "InputDevice"
    # generated from default
    Identifier     "Mouse0"
    Driver         "mouse"
    Option         "Protocol" "auto"
    Option         "Device" "/dev/psaux"
    Option         "Emulate3Buttons" "no"
    Option         "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"
    # generated from default
    Identifier     "Keyboard0"
    Driver         "kbd"
EndSection

Section "Monitor"
    # HorizSync source: edid, VertRefresh source: edid
    Identifier     "Monitor0"
    VendorName     "Unknown"
    ModelName      "Chi Mei Optoelectronics corp."
    HorizSync       30.0 - 75.0
    VertRefresh     60.0
    Option         "DPMS"
EndSection

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "GeForce GT 540M"
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    24
    Option         "TwinView" "1"
    Option         "TwinViewXineramaInfoOrder" "DFP-0"
    Option         "metamodes" "DFP: nvidia-auto-select +0+0, CRT: 1680x1050 +1920+0"
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

here is an example of what i'm talking about: http://i.stack.imgur.com/vrlW1.png

how can i fix this? thanks in advance.