By now many consumers are aware that the music industry is beginning to press audio discs that have been copy protected to prevent them from being ripped to MP3 on a PC or Macintosh. But did you know that in some cases, if you insert such a disc, you might not be able to get it out again?
The problem is documented in a recent Apple Knowledge Base entry entitled Mac OS: Cannot Eject Copy Protected Audio Disc, Computer Starts Up to Gray Screen.
These discs aren't strictly CDs, according to the technical definition of the term, since they don't follow the basic CD standard for how data should be written to a disc. Even though they're labeled "Will not play on PC/Mac," there's still a risk that Mac users may insert them in their systems.
According to Apple Computer, when such a CD is inserted, the CD isn't recognized, and when the Mac is restarted, a grey screen can appear that prevents you from doing anything further. If your Mac lacks a manual eject button or pinhole for its optical drive, you may be stuck that way, too -- Apple offers some advice for what to do under those circumstances.
The documentation provides instructions for forcing your Mac to boot into Mac OS X on restart (holding down the X command on boot) or to force-eject a CD on boot (by holding down the mouse button when the Mac starts up). Forcing the Mac to boot into OS X won't eject the disc arbitrarily, but you may be able to by clicking on the Eject button in iTunes or DVD Player.
There's one other extreme option, too: Booting into Open Firmware and using a command line prompt to force the CD to eject, as well.
If all else fails, Apple noted that you could bring your Mac to an authorized service center to be fixed. But probably the best solution is just to avoid using these audio discs all together.
A list of some of the affected discs is provided in Apple's documentation.