I am looking for suggestions to resolve a problem I am having. When I try to run a game (Unreal Tournament or Doom) my display starts acting up. I will get multiple desktops overlaying each other the right half of the screen is overlayed with the same screen it looks similar to a mirror on the right side of the screen. The problem starts when I start the game and only stops when I log out.

Celeron 700
256 ram (16 shared with video)
mandrake 9.1
KDE desktop (same problem with Gnome)

I would appreciate any suggestions. The display only does this with these 2 games.