Just picked up a used Ti800 Powerbook that is in great condition. However, I'm having lots of problems with the Combo drive. The drive won't read CD-R media!! Retail DVD's and CD's work fine and the drive burns fine, but whenever I put a pre-burned CD-R into the drive it just clicks away trying to access the disc before finally freezing the computer even right after burning a disc and trying to mount it. Does anyone have any experience with a Ti800 combo drive? Is it picky about the brand of media it uses? The guy that sold this to me says it's not a defective drive. What I need to know is: Is the drive defective, or are these drives super picky. Thanks.