Very Computer

Hi Everybody.
 I had passed through many stages of problems in installing Linux and
 configuring X. now everything looks to be working fine. The latest problem is
 now that when i run X and quit out of it, my screen is all messed up and there
 are a lot of white vertical lines and i could not see my screen. I can however
 make out the position of the cursor behind the lines. I checked a lot of
 places for a solution, but no help anywhere. Could someone who know of a
 solution to this problem kindly let me know.

 thanks in advance.