PC Crash shortly after startup

[Atlas29]

Hello community.

I am having some trouble with my PC, which is currently crashing after a few seconds after i initiate seemingly any process after startup (not including start up processes).
The screen goes rainbow colored (as in graphic card error) and freezes or freezes and starts restarting. Then i restart it/let it restart itself and the computer is completely fine, after either first or second attempt of this. Usually first.

I would like some suggestions of how to fix, preferably without re installing windows or changing hardware components.

I have:
win7 64 bit
ATI Radeon HD 4800 series
i7 860 2.80 ghz
4 gb Ram

My graphic driver have been updated using catalyst control center.

I would be grateful for any suggestions

 

[Entomber]

well, your problem appears to be a hardware problem so it doesn't seem to be fixable without replacing your GPU.

 

[Atlas29]

Since it is something which only happens on first startup and not restart, it suggests to me that there very well could be a software solution to this problem. If it was solely a hardware problem, i cant see why it only crash on first startup.