" A lot of spontaneous reboots and things like that are cause by video drivers."
Well, one of the causes of them! ^_~ the other things mentioned will all cause the same symptoms - but yes! I didn't even think of video drivers - those could be a possibility too.
You're right Cavanaugh - 41C isn't too bad - and I'd think it would probably be better with it on the cart rather than under the desk.
If it isn't video - what about your memory? Are you using aggresive timings? That usually doesn't cause /shutdowns/ - but I've seen it cause odd problems and STOP errors.
If it is shutdowns, and not reboots, I'd be inclined to rule out video - but it never hurts. Check the temperature monitor in your BIOS settings too - sometimes those are set ridiculously conservative. There's just so many things it could be: Power supply, cooling, drivers, memory timings, other BIOS settings, CPU going flaky on you...
