I'm seeing exactly these symptoms with xserver-xorg-video-vesa 1:1.3.0-1 for i386 >From my /var/log/syslog: Jul 25 23:36:12 Valiant gdm[3392]: Xinerama active, but <= 0 screens? Jul 25 23:36:32 Valiant gdm[3384]: gdm_child_action: Aborting display :0