This is a 2011 15" unibody macbook pro with dedicated graphics (AMD 6770 graphics I think). The screen went grey while scrolling through a PDF. When I forced it to shut down, it would restart only as far as the login screen, then it would go grey again while trying to complete the restart. The next morning, it turned back on and was usable for a time. Then it froze again, the screen going pink (it seemed to draw that color from a webpage it was on when it froze). I cannot access the drive from another mac on the same network. Anyone want to venture a guess as to what this is? Bad RAM? Graphics card? Possibly this: http://www.apple.com/support/macbookpro-videoissues/ Thank you for any help!