The '00 528i I just bought had a cd changer that said "no disks", even though there was a cartridge full of disks in the unit. A forum member "frank3" in California suggested to someone else last July to "bang on the changer" while it was going through the CD check process. IT WORKED!! Who needs hi-tech fixes when a good bang will do the trick!
Thank you, frank3!
Bob in Houston