For the past month or so, my computer has been freezing immediately whenever I load any sort of 3D game or application. At first it was just freezing on the last frame to be drawn. After a week or so of that the screen display would be corrupted when the freezes occured, drawing all sorts of insanity everywhere. A hard reboot is the only way to get out.

Applications that I've verified to freeze: Half-Life (including mods), Ghost Recon, Tony Hawk Pro Skater 2, Everquest, Grand Theft Auto 3, & Worldcraft. Note that Worldcraft (level creation application for Half-Life) never freezes when the 3D view was set to wireframe, or flat surfaces mode. It only freezes/corrupts the display when in textured mode.

Applications that do not freeze are most 2D ones including: Age of Empires/Kings, Autocad, Adobe Photoshop. Video software/playing videos do not cause freezes either.

My machine is a fairly old beast, but it has always run well up until now. It consists of:

AMD Athlon 650 Processor
FIC SD-11 Motherboard
GeForce 2 6400 MX video card
Sound Blaster Live! sound card
256mb PC100 SDRAM (on two dims)
18GB 7200 RPM Hard Drive
Windows 98 OS

The most interesting thing to me is the progression in the freezes. They began fairly rarely, and quickly became more and more common. At first, the system would freeze for a few seconds, and then recover. It then started to freeze entirely, requiring a hard reboot. Then it began to corrupt the display upon freezes, again requiring a hard reboot.

I had made no recent hardware or software changes prior to the problems. They just started happening without any explanation. I have heard many theories on what could be causing this. Overheating video card, bad sound or video drivers, failing RAM, etc.

I am not a total computer geek, but I have tried the things I can, including:
Thoroughly cleaning every area of the case/CPU/video card
updating to the most recent detonator drivers
updating to the most recent sound blaster drivers
changing, raising, lowering acceleration/display settings
updated directx to version 9.0b from 8.1
I also removed a seperate partition which had Linux installed on it. I doubt it had anything to do with the problem, but I no longer needed Linux anyway. :P