It sounds like you have a driver conflict. First go to Device Manager (via Control Panel), and look to see if there are any yellow triangles with an exclamation point. If there is, open the tab its on and see what its telling you is wrong.
If there are no yellow triangles, go to the tab labelled Video, sound, and game controlers and open that tab up. What and how many drivers are listed for your video card? If its more than one, uninstall the old one and see if that resolves the issue for you.
Hope this helps.