https://bugs.freedesktop.org/show_bug.cgi?id=35697
--- Comment #8 from Mario Kleiner mario.kleiner@tuebingen.mpg.de 2011-03-27 13:55:39 PDT --- Pure guesswork, but maybe worth trying:
Can you check in your ~/.kde/share/config/kwinrc if setting the option UnredirectFullscreen to false...
UnredirectFullscreen=false
...and restarting kwin makes any difference?
-mario