My girlfriends macbook (aluminum) crashed about an hour ago while she was on facebook and said it showed a black screen with green lines. When she restarted, it was just a black screen, preceeded by a spinning circle below the apple logo. A few weeks ago her computer also crashed and her boot got corrupted. Could the former crash be affecting this problem? How can I fix this problem? I have the install disk and her computer is backed up with time machine on an external HDD. Shes coming over in an hour and I need tips on how to get things running smoothly again. Thanks .