I've just been attempting to get prepared to update this laptop to 
4.0rc3 from 4.0rc2 but found my network connection is now only one-
way. Ftp or nfs transfers to the laptop are about 6 MB/s but on 
outgoing connections I just get 'rtk0: watchdog timeout' after a few 
100k of transfer.

On NetBSD 3.x then 4.0Beta2 I didn't notice any problem but mostly 
network traffic would be into the notebook. Generic kernel causes 
various problems such as complete lockups so I'm using a custom 
kernel that has as much unused from Generic removed. I've been really 
pleased as I eventually have sound working and glxgears gives 80fps 
which are both an improvement over all the Linux distros I've tried.

I'll go back to nearest to generic and previous non acpi kernel as on 
LiveCD to do some more checking.

What else should I be looking for?

David