winxp and geforce4 4200 lock ups

[HomeYield]

This is driving me crazy people. During any game, my computer can completely lock up (ctrl-alt-delete does not respond). The screen all the sudden becomes granulated and fuzzy and locks up the computer. If I press the reset button instead of doing a hard shutdown, the bios screen comes back really garbled just like what it looks like when it locks up. I have to shut down the computer completely, give it a few minutes and then I can turn it back on.

I'm running winxp pro on an asus a7a266, 1GHz oc'ed to 1.2, 512megs ram, gainward geforce4 ti4200 64MB ram. I've tried drivers from 29.xx up to 40.41, all with same result. I've updated my motherboard bios, I've underclocked the graphics card, overclocked the graphics, reset my processor to default, and I'm still getting locks while playing Max Payne, Quake3, Morrowind and anything else. I was, however, able to run 3dmark2001se. My score didn't even break 6000.

I'm doing something wrong here and I just can't put my finger on it. Any and all suggestions will be greatly appreciated.

Thanks everybody.