This has been going on for some time now. When I put a DVD in -- does not seem to matter much whether it was a commercial, pressed disc or one that I burned, although the issue is somewhat more evident with those that were burned -- it will spin up and then say "Unknown Disc." If I jiggle the disc around a bit in the tray, and close the tray again, from between, say, 3 to 5 attempts, the disc will then be recognized, and play just fine all the way to the end. (I hope I haven't asked about this before, but I don't recall . . . .) It seems like something is starting to become unreliable. The laser ? Is this a common problem. Is there a way to "clean something" and ameliorate this for a decent period of time ?