Actually, a screen shot is a good idea. Look at the screenshot outside of your game and make sure it's still got goofy colors. Then, try some other 3d games and see how those behave. On many cards, the 2D and 3D graphics capabilities used to be separated, although I honestly don't know how true that is anymore.
If the screenshot looks normal, then you might have a problem with your card, or it could be simply a case of pulling it look, reseating it, then putting it back in. You might also have a cable problem, although one would think that would show up all the time .. unless you're running SLI, which might also effect it.
okay, brain dump/vomit complete.