Probably one for Bugzilla, but at a minimum you'd need to say what
desktop environment you use, and preferably which distro. These kinds of
issues often depend on specific video cards, so that would also be worth
mentioning.
poc

I use XFCE 4.6.1 on Debian Squeeze (5.03) with Linux 2.6.30-2. My video card sucks for Linux it's a SiSM650 so since you metion it this may be the source of my problems...