Michael Büker <m.bueker@berlin.de> :
[...]
> With both 2.6.27.19 and 2.6.28.7, I am experiencing "transmit timed out" 
> errors as reported by the netdev watchdog, for both my PCMCIA Ethernet 
> adapters, using the r8169 and 8139too drivers respectively.

Can you describe the symptoms a bit more specifically ?

The kernel displays a scary warning, I can guess that it is almost surely
associated with some loss of network connectivity for a few seconds at the
very least but it is a bit hard to figure the real scale of your problem.

Please scare me. :o)

[...]
> as both kernel config files. I'll gladly provide more information as it is 
> requested.

lspci -vx and a complete dmesg.

Can you identify a kernel which worked flawlessly ?

-- 
Ueimor