Computer crashes please help

[mitchzero]

When ever i load a game such as Modern warfare 2 or Aion my whole pc freezes the graphics become distorted and theres a sound loop this has only recently started. my computer is not too dusty inside and Everest says it's at an ok temp.

pc spec:
Graphics: Nvidia Geforce 9800 GT 512mb
Intel i7 @ 2.67 GHz
Motherboard: Asus P6T Deluxe
9GB DDR3
Windows vista 64bit

heres a picture i took on my phone of what happens when loading a game (the same happens when its sat on screen saver)
Oh wait you wont allow me to post pictures or links.

The graphics become distorted a sound loop is constantly playing and the only thing i can do is kill the power. Please help thank you

 

[Route44]

Does this happen at any other time or with any other games? Have you tried updating your video and audio drivers?

 

[mitchzero]

It happens when i leave the computer for 5 minutes and the screensaver beings to move it does the same as ingame. I tried updating the driver after the first time but it says they are all up to date.

 

[Route44]

Do you get any Blue Screens of death?

 

[mitchzero]

Nope, it just all freezes on the spot and i have to turn off by the plug