opengl and black screen

When I run a open gl screensaver, move the mouse to get to the desktop, the screen turns all black. I have to refresh the desktop and move the taskbar out of site and then back up again to get it back to normal. I dont seem to have any problems with any games so far, but I have a lot more to try out. Could you tell me what causes this, and how I may fix it. I a have windows xp pro, intel 2.4 , ati 9700, and 512 megs rdram 1066, direct x 9, and the catalyst 3.1 drivers. I dont know very much about this subject, but i could probably understand some. Thanks for any help Mike