> Video is on the MB. It doesn't seem likely that it's
> the video, since the system doesn't respond to network
> when it crashes.
bad video hardware or drivers can easily crash the system
If its running an X windows display of any sort, I'd suggest trying it
in text-only mode. in /etc/inittab, set the default runlevel to 3
instead of 5. this leaves the video in plain VGA text mode which is
far less likely to crash the system.
id:3:initdefault:
bonus, if this is a server, and thats a shared memory video system,
disabling the graphic modes reduces the memory bus contention, speeding
up the whole system by some percentage.