8800 gtx blue dots on startup

Hey -

I recently have had a problem with my computer have weird blue dots and streaks on the bios, and windows loading screen.

It makes it to the log in screen but the whole screen is black except for a white bar at the top of the screen.

It was working fine yesterday, so I can't really tell what the problem is.

I thought maybe it was over heating?? but I usually have it running at average 50 C.

Any one else have the same problem or have a course of action I could take?

** How do you know if you can mail it back for a new one, if anything is wrong??

Thanks !