Try to deactivate visual effects if they exists in you Linux distribution
e.g. with Ubuntu 8.04 the gnome desktop environment has this visual effects activated by default
In order to deactivate them, go to:
System->Preferences->Appearance - Visual effects
and set to None
Maybe the problem is because the use of graphical acceleration, to avoid it:
Go to the GiD menu Utilities->Preferences...
and in the "Graphical" tab select the "Safe visualization mode"
Some problems could be solved also setting "Selection lines by software (emulateFronBuffer)"
Another method to do it:
instead the normal starting script
try to use this alternative starter (to use our generic mesa graphic library)