About 50% of the my NATTY desktop screen is corrupted. Once that happens I can re-boot as many times as I want but the problem continues. If I logout and then into WINDOWS for a day I may be successful and boot UBUNTU with a good screen.

The desktop is formatted correctly, there's no pixelation, rather there is a fine grained white crosshatch pattern covering the entire screen. If I open any application the screen corruption worsens eventually to the point I can no longer make out anything.

I ran ram memory test w/o any errors. I have no display issues when running WINDOWS 7.

Any ideas. My computer is a Dual Boot stock DELL 5150 w/3gig of ram an on board video.