Flash and games in KDE 4.2

[no4b]

Fullscreen movies from youtube don't work in KDE 4.2. If I press fullscreen button screen is getting black (slowly) and I have to press alt+tab to switch to another application. I have the same problem with games, for example teeworlds. It doesn't matter if I have effects turned on or off.

You can watch this: http://82.115.67.2/~abaddon/fullscreen_problem.avi

It looks like 1 frame per few seconds is drawn.

Do you experience something similar? How to fix it?
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GTK2/GNOME - The weakest link!