Could be your video card is giving up and needs replacing. Try to use it in another system. Or you can plug your monitor into another system. Either way that should isolate your problem. If the monitor checks out, you replace the video card and it still won't work right then we look at the motherboard.
and life goes on...
I have a Dell M991 monitor and use Nvidia Geoforce FX5200 display adaptors. It is a Dell 8300 and I run xp Pro.
When I turned on the maching yesterday, all the colors looked muted - where red should be in icons only black, no red in any of the cards, photos well I just simply closed photo preview. I got on line with Dell support and we changed the color quality to 32 bit, and the screen resolution is at 800x600 since I require larger icons and text than normal. I uninstalled the driver and reinstalled the new one although no new driver was found. I did a restore system to a previous date but no change in color so I returned to original date. Please help me as I would to look at my grandchildrens photos and right now the color is so faded that I prefer to wait until this problem is a last nights dream. Thanks, MamaJen