So, earlier, I went to eject a DVD from my Macbook. It ejected fine, and then I inserted a CD. Now the Macbook won't recognize the disc. It sounds like it keeps on trying to read the disc. When I press eject, the Macbook makes the sound like it is ejecting it, but it never comes out, and after a moment, it makes the sound like it trying to read the disc again. What should I do, and how can I get the disc out?