Yep, same problem here.
Same graphics card also.
Only at night i see strange shapes, i tried to make some screenshots to post this problem but believe it or not, the strange colours and shapes do not show on the screenshot.
Screenshot looks normal, so it's extra difficult to explain to people what i actually see. grrrrr!
Don't have any problems though inside the sub, only exterior at night.
Please inform me if you would find a solution, i would appreciate it!
Good luck,
fvd