Sometimes i put a dvd in my powermac quicksilver g4 733mhz 640 ram and certain dvds just wont work . After i put them in for instance Bad Santa right now it takes about 10 seconds then no disc icon appears and the drive just opens up again. Its like it wont aceppt the dvd. I just put it in my mothers new ibook 1.33ghz i believe and it works fine and reads and plays the disc. Any thoughts this has happened to me with certain dvds , although it is rare. Thanks