Certain music CDs fitted with digital barriers to stop copying can also cause some Apple computers to crash and refuse to spit out the incompatible disc. The CDs are designed not to play in personal computers as a deterrent to digital copying. Each CD comes with a small warning label: "Will NOT play in PC/Mac".
The CDs can cause Mac computers to freeze and then reboot to a grey screen, according to an Apple technical support report. The computer may then refuse to restart until the CD has been manually ejected, which may not be possible without opening up some parts of the machine. However, the problem does not cause any permanent damage to the computer.
Apple spokesman David Millar says: "It is not unusual for people to expect to play their CD through their computer." He says even clearer labelling may be required.
"Apple can't really be blamed for this. The warning isn't the whole truth," says Jim Peters of the UK's Campaign for Digital Rights. Peters believes the consequences of attempting to play a disc should also be made clear.
The protection system used on the CDs causing this effect is key2audio, created by DADC, a subsidiary of Sony based in Austria. The system is used to protect a number of European music CDs, including Celine Dion's "A New Day Has Come", Shakira's "Laundry Service" and "J To Tha L-O!" by Jennifer Lopez.
A spokeswoman for Sony DADC, Sandra Wieflingseder, says the CD was tested on many different kinds of PC and Mac without this problem. She says the CDs could always be ejected using the manual eject hole as a last resort.
However the Apple support article says: "Some computers, such as the iMac (Flat Panel), Power Mac G4 Cube, and certain models of Power Mac G4 (QuickSilver or later), may not have a user-accessible eject hole". In this case, the computer would have to be taken in for repair.
Apple's David Millar adds that the problem may depend on the particular software installed on a computer as well as the type of CD inserted. He says there have been a few reports of the problem at Apple's UK support centre. One UK Apple retailer, Gordon Harwood Computers, says that a flat-panel iMac sent in for repairs had to be partially dismantled in order to remove such a disk.