You don't seem to have anything special in your xorg.conf, can you try moving it aside (sudo mv /etc/X11/xorg.conf /etc/X11/xorg.conf.bak) and restart X? If that doesn't help it's going to be a driver issue.
You don't seem to have anything special in your xorg.conf, can you try moving it aside (sudo mv /etc/X11/xorg.conf /etc/X11/ xorg.conf. bak) and restart X? If that doesn't help it's going to be a driver issue.