Random crashes like that are typically related to heat, driver issues, or a
problem with the game. Since it happens every time you play "a game" I'm
assuming it's more than one game so I'd investigate the driver and heat
issue first. Make sure your motherboard's chipset drivers and the drivers
for your audio and video cards are up-to-date. Dust out the inside of your
computer while you have the case open and make sure all fans are working
properly and are free from debris.
If you've got a PCI card right next to your display card consider moving it
to another slot. It could be disrupting the airflow enought to cause
overheating issues on your video card. If that doesn't alleviate the issue
you can try adding one of the PCI slot fans that exhausts hot air from the
bottom of your case.