Wierd graphics problem

This happens almost every time i play a game, right now its starcraft
I can play for anything between 5 minutes and 4 hours before this problem occur, so it seems its random.

The screen goes all flickry, lines running through the screen.
I have no idea what causes this, but it only occurs when i am watching movies in fullscreen or playing a video game. When this happens, i can continue playint with the flickering, until it (sometimes) lock up, or try to exit the game, wich will do a 100% lockup. No keyboard commands work, i have to physically reboot the computer.

I will upload a screenshot in a moment.


What can it be? Is my graphics card broken? (But why then does it only happen sometimes?)

PS: In the screenshot, normally you can see the game in the background (black areas), i just tried to quit the game wich made it black .

 

Whats your system specs, (specifically the graphics card) and check the airflow in your case, make sure the GPU isnt overheating.