I'm a very bitter man right now. My MacBook is a victim of the random shutdown problem that some are starting to complain about. I got fed up with it and took it the Genius Bar last Tuesday. I picked it up tonight and was told they ran an 8 hour diagnostic with no problem and they replaced the top case. Great... or so I thought. I got home and the damn thing wont even boot up properly. It freezes at the white screen and slowly these multi-colored verticle lines appear. Below is a pic. Has this happened to anyone else?