Computer crashing on startup

So, my computer is working fine for a minute-few minutes and then crashes after the screen goes all weird with alternating black and white rectangle areas. I have no idea what to do, and there have been no previous issues.

if it crashes on startup, how are u typing this message ?

Different computer.

Alright, more information. I'm typing on this computer, because it doesn't always do that. It seems like if I turn off the power supply for a while, it resets the video card, and then it will work for a while.

sounds to me like your power supply is going on the blink and it could also be causing your video card to fail because of lack of power.

do you have the system spec's?

need to know what video card and what power supply you have... all other hardware would be good too. It does indeed sound like a faulty PSU, but it could be a cable that came loose (happens once in a great while) or a driver issue, or even a virus.... but based on the initial information (rather limited as it is) I agree with Fifi ^^^