In most cases the default X install on freekboxen will just work, but in some cases it needs some tweaking. On Ubuntu systems, you can use "dpkg-reconfigure xserver-xorg" from a root terminal to reconfigure the X server, but there are also several easier methods depending on the exact distribution.
Editing the configuration file
The X-windows system configuration information was previously kept in text files in /etc/X11 in a file /etc/X11/xorg.conf. This file is now intentionally blank as X will auto-configure. Very occasionally, the normal methods of configuring X fail and we need to edit/create the file directly.
Don't edit this file unless you REALLY know what you are doing.
This file includes information on the keyboard, mouse, monitor, and video card, as well as some special options for resolution, fancy graphics display, and multi-headed systems. The file is broken up into sections such as
"InputDevice" for mice and keyboards,
"Monitor" for monitors, and just plain
"Device" for video cards themselves. The
"Screen" section has meta information about combining all the pieces together correctly.
Since this is file is blank you need only add the relevant section. Do not blindly add others.
You will need to test your changes by running
sudo /etc/init.d/gdm restart
If this doesn't work again, check the log file:
and try again.