Leo says intermittent problems are frustrating because they don't happen all the time. Dr. Mom in the chatroom thinks it may be a loose wire at the hinge. Older MacBooks had an issue of running hot and that could be it, or worse case - a cracked motherboard, which would be an expensive fix. Or it could just be a loose connector that can be fixed easily by re-soldering it. Leo advises taking it to an authorized third party who will go the extra mile to save him money and solve the issue.