I have a Mac OS X computer that I have played various CD's & DVD's on with no problem. Purchased a new DVD & cannot make it play through & have had to shut down to eject the disc. I have tried 2 DVD's from the same company with the same results took 1 of the DVD's to a DVD only player & it seemed to play with no problem. Why would this be? I played a different DVD after I had the problem & it played fine.