I am useing KDE 3.5.6,  When I dismiss a panel or desktop menu without selecting and option I often get a black hole in my background, this hole can be removed by moving a window or icon over the sport or refreshing the desktop, GNOME and XFCE not not exhibit this behavior, and I have not been able to reproduce it using any other distros live cds. 

Does anyone have any ideas what could be the culprit?