Try upping your color depth to 24/32bit. I'm guessing this might be the cause. Also run find out who makes the chip for your video card and run to their site and look for reference drivers.
If you don't know who made the chip for your card put the name up here and I'll tell you who and give you the chips site and a few fan sites.
If you don't know who made the chip for your card put the name up here and I'll tell you who and give you the chips site and a few fan sites.