[K12OSN] One terminal frequent random crashes

[Krsnendu dasa]

I have one terminal (the most important one, the secretary's office
computer) that has begun crashing frequently and randomly since
Friday.
All of a sudden the screen goes blank then after a short time returns
to the log in screen.

The other terminals seem to be working ok.
The only change I can think of is that the secretary began using
publisher with Crossover Office on Friday. She has not been using
Publisher since then, but she has continued to use Crossover office
for MSWord etc.

Another possible change is a change of printer. A Brother MFC 7420 usb
printer was broken so it was sent to be fixed. In the meantime we
switched to an HP parallel printer and now have switched back to the
Brother USB printer. Both printers seem to have been working normally.

Our setup here is two ltsp servers using dhcpd loadbalancing. /home is
on one nfs mounted on the other. The office terminal is set up in
lts.conf to always connect to the server with /home regardless of
which dhcpd server picks up the ip address request. Perhaps there is a
conflict between the two servers?

nbd swap is enabled.

Where should I look to source the problem?  I thought of /var/log/messages
Any other suggestions?