My ethernet-based network connection doesn't stay up consistently. I'm running a ping against the gateway and it will:

• Work for a minute
• Freeze, time out, or give multi-second response times
• Repeat

If it's stuck and I disable/enable networking through the network manager applet everything will work fine again for a minute. After 280 packets transmitted I'm getting 41% packet loss. I've tried a different cable and connection to the gateway but this had no effect. The distance to the gateway is just about 3 feet.

Seems to work fine if I switch over to Windows, but Ubuntu is my main OS and I can't even use it right now as I depend on the network.

My setup...

• OS: Ubuntu 11.04, dual-booting Windows 7
• Mobo: Gigabyte Z68X-UD4-B3
• CPU: Intel Core i7 2600K

Edit

A little clarification... Network Manager is still showing me as connected, but I am unable to reach to gateway or anything beyond. At no point does NM suggest the connection is lost and calling ifconfig shows that I still have an IP address.

I tried connecting to a different gateway with a different cable and the same problem arises.

As requested:

lspci | grep -i eth
07:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 06)

dmesg | tail -f
[   14.024709] EXT4-fs (sda5): re-mounted. Opts: errors=remount-ro,commit=0
[   14.026443] EXT4-fs (sda7): re-mounted. Opts: commit=0
[   14.176101] hda-intel: IRQ timing workaround is activated for card #2. Suggest a bigger bdl_pos_adj.
[   23.917731] eth0: no IPv6 routers present
[  726.109697] r8169 0000:07:00.0: eth0: link up
[  733.169494] r8169 0000:07:00.0: eth0: link up
[  753.930119] r8169 0000:07:00.0: eth0: link up
[  880.787332] r8169 0000:07:00.0: eth0: link up
[ 1159.161283] r8169 0000:07:00.0: eth0: link up
[ 1406.623550] r8169 0000:07:00.0: eth0: link up

Edit

@roland-taylor: Network is always available under Windows. Pings do not timeout, applications do not complain of no network availability, large downloads are not interrupted or slowed.