The computer is a Dell D600, with an ATI Radeon Mobility 9000. The OS is SuSE 9.1, updated religiously. Today's installed RPMs include kernel-default-2.6.5-7, XFree86-4.3.99, fglrx-3.12.0 (ATI's driver), and KDE 3.3.1.

Every now and then (sometimes once a day, sometimes once a month), the desktop stops responding. The cursor follows the mouse, but clicks and keypresses are ignored -- even Ctl-Alt-Delete, Ctl-Alt-Backspace, and Ctl-Alt-F1. This usually happens when I'm scrolling BoingBoing.net (a long page) in Konqueror, but I'm pretty sure that's not the only program that triggers the bug.

The machine can be pinged, and I can slogin from elsewhere. When I do, I find X consuming at least 99.8% of CPU. Killing X causes a complete lock-up; it won't answer pings, and I have to power-cycle the computer. /var/log/messages contains nothing between the slogin and the restart.

I've had the problem with KDE 3.2 and 3.1, with fglrx 3.11 and 3.9, and with XFree's default "radeon" driver.

Have you seen behavior like this? Do you have any suggestions?