*Extremely* peculiar OpenGL issue

About 2 weeks ago, during which I was playing Counterstrike and Firearms for Half-Life using the newest NVIDIA reference (official, not leaked) drivers, it just spontaneously started to lockup my system. After that point (before which I changed absolutely NOTHING in my system, hardware or software, installing or uninstalling), EVERY game that uses the OpenGL API locks up within an hour of playing, but usually within 2 minutes. Direct3D, you ask? No problem. Unfortunately, most games that support OpenGL run like frozen **** if they even support Direct3D, and this is a major issue with many new games I own.
Let me present to you a tidy list of everything I’ve tried in the past 2 weeks to resolve this issue:
-Removed modem
-Removed sound card and ALL drivers
-Disconnected CD drive
-Formatted ENTIRE hard drive manually and reinstalled Win98SE directly from disc.
-Contemplated suicide.
-Tried different stick of RAM
-Tried different (but same model) video card that works fine in a similar system
-Removed EVERY component from system that’s not soldered on, unplugged system, let it sit for 12 hours (seriously.)
-Tried GLSetup (which just reinstalled 6.50 NVIDIA ref drivers - yay.)
-Tried 17 different versions of drivers from Asus and NVIDIA (up to 12.00 from NVIDIA)
-Triple-checked every file in my 6.50 NVIDIA ref set and opengl32.dll with many other systems that work fine; they’re exactly the same to the byte.
-Tried every BIOS trick mentioned in the GeForce FAQ ( http://www.tweak3d.net/faq/ )
-Tried mouse in both PS/2 and USB ports.
-Disabled both serial, LPT/parallel, USB ports, onboard audio (was disabled anyway)
-Disabled ACPI (was anyway)
-Disabled power management entirely
-Disabled gameport/SB16 emulation
-Monitored temperature and voltage of video card. No change since before the problem manifested itself. Illogical since another video card didn’t work anyway.
-Using newest BIOS
-Tried File Checker as suggested in another post
-Tried RAM in all 3 slots
-Fooled with every single option there is in advanced NVIDIA properties
-Totally cleared out BIOS, loaded from ROM, then reset all my options.
-Tried other refresh rates

I’m sure there’s more I missed, but you get the idea. :stuck_out_tongue:
Also, USUALLY the type of lockup suggests my video card is somehow damaged (though it obviously isn’t) - perfectly straight vertical lines throughout screen and, when enabled, high-pitched beeping emits from speakers. Sometimes, though, it just locks up without many anomalies - just a few pixels ‘transported’ to another part of the screen. Very very odd.
The weirdest part is that this appears to be a hardware issue, but since it only occurs in OpenGL and I’ve tried different hardware except the processor itself, you’d think it’d be driver-related… but how? Total format, checked all Open-GL related files.
My system specs:
-Epox 7KXA motherboard (served me well for over a year)
-AMD K7 800 MHz Athlon processor (original)
-Corsair PC133 256MB SDRAM
-Asus 6800 Pure (GeForce DDR) (tried both Video BIOSes, don’t care to try NVIDIA one)
-SB Live! Value + LiveWare 3.0
-WD 20 GB UDMA-66 7200 RPM HD
-Zoom 56k modem
-Really big heatsink/fans on my processor and a few in the case, so heat isn’t an issue
-300-watt power supply
-NEC Multisync 90

Any suggestions at all would be very appreciated. I’m on the brink of… dare I say it… buying a new system. This one’s just over a year old. I’d like to keep it for another few.

Oh yeah, I also tried uderclocking my Core and video memory speeds.