Hi, i am having the same problem i think. I have a HD3000 IGPU on a i5-2500K Desktop CPU and i'm running Debian Wheezy with KDE. The way to reproduce the issue is to click or change very fast the screensaver in the KDE-Settings. You have to change the OpenGL- Screensavers very fast by clicking on the names of them. After a few clicks (5-15) the Xserver freezes and i'm only able to move the mouse, nothing more. Regards Bentallica