On NetBSD/i386 1.5ZC with XFree86 v3, I'm seeing occasional lockups.

Randomly, but usually after an hour or two, I get:

pms: resetting mouse interface

on the console and both mouse and keyboard lock up.
The mouse is a 3-button PS/2 mouse; the keyboard is a regular PS/2
keyboard. Other than logging in and killing processes, I cannot do
anything at the console.

Any ideas? 

cheers,
Chris