Ubuntu screen resolution

This starts the Xorg config process.

sudo cp /etc/X11/xorg.conf /etc/X11/xorg.conf_backup
sudo dpkg-reconfigure xserver-xorg
sudo xinit -- :2

Look for errors:

tail -f /var/log/Xorg.0.log

Restart all servers by bouncing XDM (or gdm or kdm):

sudo /etc/init.d/xdm start

This starts a new X server -- usually on tty8 or tty9 (CTRL-ALT-F8). You can go back to the original X server by pressing CTRL-ALT-F7.