If you don't mind some advice from a computer tech;
it may be your power supply failing to supply proper voltage to your card, or it may be heat from things that are overclocked causing instability under stress. When it isn't a driver problem these are the most common issues with hardware that hasn't failed outright. ANd as your problem started without you doing anything, the power supply dying is my best guess. If your bios has voltage monitoring built in check out the readings... If your 3.3 volt line is reading 3, or your 5 volt 4.7 etc..., try a new power supply.
Also, check the fan on your video card and in your case, make sure they work, if the fans seem to be working well try raising the voltage a tiny bit (~5%) on your ram and CPU.
If that doesn't do it, a geforce 2 is a Dx7 part, it does not support all the features of dx8 much less dx9. These are handled in a software emulation mode, it may well be that your box is just not stable enough to handle the stress of emulating the hardware. I'd check your ram timings (if they are 6-2-2 set them to 7-3-3 or 8-4-4) and if your box is already overclocked set it back to the default bus speeds.
Good luck
