I've had success after rebuilding the xserver-xorg and xserver-common packages with this patch as suggested by dri-devel folks: http://lists.freedesktop.org/archives/xorg/2005-December/011679.html This fixed the lockups on startup and also the VT switch problems. I also installed the patched packages on my desktop which has a "Radeon 64MB DDR" (R100 QD) and it doesn't cause any problems there.