Brief and intermittent system freezes

[Yuri]

I changed the motherboard on the 10.3 desktop system and now I am 
getting the "sticky mouse" effect: mouse briefly freezes every few 
seconds. I think USB mouse events aren't propagated to the Xorg process 
in a timely fashion. This also possibly makes the system impaired in 
some other ways too. One thing I can think of is that the network driver 
changed from re(4) to msk(4).

What is the best way to troubleshoot such problem? Anybody experiences 
something similar?

Thanks,
Yuri