display driver has stopped responding fix

Question

I have a nvidia geforce 9800 gt, 2gbs of ram, amd quad core. It happens a boat load on cod4, but i recently downgraded to a driver that was reported to fix it, and when playing minecraft it only freezes once every 20-30 minutes, as opposed to a dreaded every 3-8 seconds. PLEASE help any information would be good. I have tryed the Regedit d/q word fix, updated downgraded drivers, even installed my previous card to check to uninstall the drivers again.