Just began having this problem with my new(ish) 17" MBP. It only occurs w/ audio cd's (store bought ones). They are immediately ejected and will not mount. DVD's mount fine, Software and Data disks also mount fine. Seems pretty odd. Saw other folks on the apple boards having other kinds of issues but they weren't able to mount any kind of disk. I'm hoping its a software rather than a hardware problem. "Genius" diagnosis: archive and install (yawn...is this the only advice they have?!) I keep thinking it might have something to do w/ itunes...anybody?