anyone have any suggestions? there's no CD currently stuck in the drive, but that's what it feels like. can't get a CD more than an inch or so in, something is blocking the path. maybe the motor that pulls the disc in is shot?
No idea why it won't let you insert a CD. But to make absolutely sure there isn't a disc already in the drive, shut down, then keep the trackpad depressed as you press the power button to turn the Mac on - this will force the drive to eject any disc that might be in there.
Another option is to boot up in hardware test mode - the same procedure as above but keep the 'D' key held down (as opposed to the trackpad) when you turn it on. It takes a while for the hardware test mode to kick in but then you can run a test which ought to tell you if there's any problem with your CD drive. Running a hardware test can be enough in itself to eradicate some problems - my hard drive had a massive freakout last week and just entering hardware test mode and running a test seems to have magically resolved it. If the worst has happened, and it gives you an error code or reference, call or email Apple quoting the code and they'll authorise a repair. Are you still under warranty / an Apple Care extension?
for anyone who might care, my issue is resolved: brought it in to the apple store genius bar, turns out an internal part in the optical drive had come loose and was blocking the pathway. had to replace the optical drive...however, it also turns out i was still covered by applecare, so no charge (instead of $151)! i got my MBP in 2009, thought i'd gotten one-year coverage but apparently i got the three-year package, woohoo!