The laser in it might be misaligned. You would have to get it checked out by an authorized repair person. It usually cots about $25-$50 to repair. I had it done and mine has lasted nearly two years.
I sounds like you have some type of serious internal problem. First thing though I would check to make sure the audio and video cable where in all the way.
There are a few things that it could be including a bad or loosely connected video cable. If the humming sound is not normal, then it needs professional service.
