If you tried a cold reboot, and still you get a garbled display while using the original xorg.conf configuration file that worked correctly previously, and with the resolution that worked previously, then it's sounding like your video card is having hardware troubles.
Otherwise, if the video card is known to be good (like it works fine from Windows or whatever) then most likely the problem is with your Linux video driver.
Please tell us what Linux (and version) this problem is happening on, and if possible, from a VT perhaps, please give the output of the commands:
shell$ lsmod #this one will only help if X has been started
and tell us if this is a laptop or desktop machine.
Last edited by GrapefruiTgirl; 09-18-2009 at 11:37 AM.