That is weird. The only thing I can think of is maybe you have the wrong video driver installed... what kind of video card do you have? If it's nvidia, you can get drivers from
their website. Search these forums if you have questions about installing nvidia drivers, since it's a pretty popular chipset.
Also, I had similar problems with my Creative Savage4 blaster card. Never did manage to fix it, but I didn't look too hard for drivers.