Computer freezes when playing jka
 

So when i play jka (this only just started a few days back) and when i play after a few seconds or minutes random models or meshes / map parts start to flicker and later the screen starts to to go black and then it ends like a sound keeps repeating all the time and i am frozen (not just the game but the whole computer) or my monitor loses its signal.
I have to do a reboot to fix this and i would very much like some one to give me a solution to this problem.

Thank you in advice -Resuru