I have a 12 inch Powerbook G4 and my CD/DVD drive randomly stopped working. When I load a cd, it will spit it right back out or not show up on the screen. If I try to burn a cd on I-Tunes, it says "insert blank CD", which I do, and it spits it back out. I have tried using several CDs and resetting the PRAM and PMU. Please help!! Thanks