ubuntu feisty fawn herd-1, kernel 2.6.20-2-generic, using SMP. The network interface is an onboard device of the asrock conroe945g-dvi mainboard.
01:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 01)
Subsystem: ASRock Incorporation Unknown device 8168
Flags: bus master, fast devsel, latency 0, IRQ 17
I/O ports at e800 [size=256]
Memory at febff000 (64-bit, non-prefetchable) [size=4K]
Expansion ROM at febc0000 [disabled] [size=128K]
Capabilities:  Power Management version 2
Capabilities:  Vital Product Data
Capabilities:  Message Signalled Interrupts: Mask- 64bit Queue=0/1 Enable-
Capabilities:  Express Endpoint IRQ 0
Capabilities:  Vendor Specific Information
using the module r8169 (
vermagic: 2.6.20-2-generic SMP mod_unload 586 )
after some minutes of using the pc as usual (light browsing etc) the message "NETDEV WATCHDOG: eth0: transmit timed out" appears in the system log and the network connection fails.
ifconfig to activate/deactivate the device does not help. removing the module is not possible as it is in use. reboot helps :)
Solution as suggested by (german!) http://www.hosteurope.de/faq/index.php?cpid=12346 is to turn off TSO ("TCP Segmentation Offload") with "sudo ethtool -K eth0 tso off".