I've using my Superdrive a lot recently for various reasons. Yesterday it stopped performing as it should. Here's the deal; it reads music CDs fine, makes a weird grinding noise when I insert a DVD then ejects it and when I inserted the Tiger Restore Discs it tried to spin but was unsuccessful and eventually ejected it. I also tried a blank DVD but it spat it straight back out. Any ideas? For info; the DVD's are commercial movie discs, the Cd's were commercially bought music CDs and obviously the Tiger restore DVD was an original. I have the MATSHITA DVD-R UJ-846 drive. Thanks.