http://support.apple.com/kb/TS2377
Though it only applies to some MBPs, maybe you have another one.
As the thread title suggests you use a MacBook, but the location the thread suggests you use a MacBook Pro, I am uncertain on how much more valid information I can give you. It certainly looks like a GPU defect, therefore a question or two.
Do you have a warranty or Apple Care for that Mac?
What exact Mac is it, if you don't know the exact details, it does suffice you telling us when it was bought (mm/yyyy)?