I had been using the bf's mac for few hours, browsing pages, facebooking ect. and I noticed it working hard, and the fans going like crazy. It actually appeared to freeze with a strand pixel pattern and I immeadiatley shut it down. I waited til it was cooled down a bit and turned it back on, only to see that some of the pixelation was still there on the sides. It said to restart, so I have turned it off for now. Have I totally ruined his mac? Should I wait and see how it is tomorrow before I worry to much? Thanks so much, I'm in a huge panic!