okay, all I can give you is my experience (bear in mind that I'm not an expert, nor do I work for Apple in any ways). You can clean the lens by possibly getting a can of compressed air and using that, maybe trying one of those dvd cleaning discs with the brushes on them. You may have to shut down your Mac Pro 5,1 let it cool down a bit, remove the side panel, then take out and disconnect the dvd drive, take it out, open it up and clean the lens with lens cleaning fluid (for eyeglasses, perhaps-this is just a suggestion, I've done it once and it hasn't done any harm) then put it back together, put the drive back in the sled, reconnect it, slide the sled back in, put the side panel back and restart your mac pro. if you have an air compressor, maybe compressed air from a tank, with a blowing tool (the one with the button on the top) might work, if you were gentle, I suppose. Hopefully something fixes your problem, daliah, if not maybe try repairing permissions in disk utility, if nothing works, try posting here again, and you're still having problems reading dvd's, could be the media, could be the drive needs replacing (but who knows?) replacing a dvd drive, should you need to, is very easy. In a pinch, you can use a dvd drive scavenged from a PC, as long as it is ATAPI/IDE and as long as it works
well, good luck to you
John b
