While I've never had the exact issue you've described, I find it helps to track the problem down before trying to solve it. If you have access to another video card (anything that supports 3D accel) try swapping it in after uninstalling your current card and seeing if anything fires up normally. If not, you can discount the video card as the problem.
Next, uninstall all video drivers, and re-install DirectX (latest version is April 2006, found here in redistributable format:
http://www.microsoft.com/downloads/deta ... laylang=en
)
Then re-install the latest video drivers. If the problem persists, it may be a motherboard or BIOS problem. Check the DirectX diagnostics panel though to see if it can shed some light on the subject. (C:\WINNT\system32\dxdiag.exe)
Another suspect might be your RAM -- try running Memtest86 from a floppy at bootup and let it run its course. If no errors occur, you can discount memory as a source of your troubles.
http://www.memtest86.com/
Double-check your BIOS settings to make sure it wasn't reset accidentally. I've had PCs that have on occasion forgotten how they were configured. Major PITA.
Good luck.
PS: Oo, one more thing: check the monitor refresh rate settings in your Display Properties -> Settings -> Advanced -> Monitor tab. If they're way-high on you're on a CRT, try dropping them back down a to 60 and working your way back up (if the problem disappears). If you're on an LCD default it to 60.