I have a unibody MBP with Snow Leopard on it. I haven't put a disk in it in a long time but tonight when I did, it slowly spins, etc and then ejects it in about 15 seconds. It doesn't show up in finder at all. I first put in my snow leopard disk, then a dvd, then a music cd... nothing. I went to the finder preferences and made sure everything looked ok, but no joy. Any ideas?