Xcalibur,
My bet is DirectX-8 is causing your problems...
I have a Geforce2, and 2 nights ago i installed the game "Giants", well the darn thing upgraded me to DirectX-8, i was having all kinds of Black screen issues...
Giants was crashing to Black screen, after about 1 minute playtime...(Solved it by increasing the game resolution from 800x600-nonT&L to 1024x768-T&L, go figure)
My machine Black screens if i try and use 640x480-256 color on the desktop...(weird)
and now my Halflife CS won't allow me to use the config-menu(it goes black)...(so i have to launch using Gamespy, then exit using the console command "quit"
Well, i fixed it all finally...(without reinstalling Windows)
Use this to uninstall DX8
DirectX Buster
Run that then reboot, then install DirectX7a <-my personal favorite version...
Ohhh, i also adjusted my monitor back to "plug and play"... It ended up on "default" for some strange reason... go figure...
Good Luck...