The drivers are up to date.
Specs:
ASRock 980de3 u3s3
AMD Athlon II x2 250 3.0GHZ (was overclocked to 3.6GHZ) (30 degrees celcius)
4GB Kingston RAM
500GB HDD
NVIDIA Geforce 8400GS (55 degrees celcius)
I was doing more heavy gaming than I normally doing. I was playing Garry's mod for 3 to 4 hours, Car Mechanic Simulator for a half hour, Rigs of Rods for 5 hours, and Bus Simulator for a half hour. I never had this happen before. I had a friend over and that is one reason why I was doing heavy gaming with him on his laptop.
finalruner :
Before I answer this let me tell you I have no idea why it crashed as it could be a million things due to the vagueness of your question. However I have a couple theories in mind:
-Drive is out of date: Update your Driver
To say my other theories I'm going to need your system specs to confirm it could be the problem.
Btw for future reference tell when this started to happen and what have you done recently.