[andrewas]

This does sound like an overheat issue. I would suggest drivers as well, but laptops are built to a known configuration, so it would be very rare for a driver issue to be this serious. Still, it very rarely hurts to upgrade drivers.

Also, go into control panel, system, advanced, startup and recovery, and uncheck the 'restart automaticaly' box. That should let you see the BSOD and might give a hint to whats going on.