music CDs not readable

[Mighty annoyed]

PIONEER DVD-RW DVR-K05:

Firmware Revision: Q523
Interconnect: ATAPI
Burn Support: Yes (Apple Shipping Drive)
Cache: 2000 KB
Reads DVD: Yes
CD-Write: -R, -RW
DVD-Write: -R, -RW, +R, +R DL, +RW
Write Strategies: CD-TAO, CD-SAO, CD-Raw, DVD-DAO
Media: Insert media and refresh to show available burn speeds

no longer reads music CDs of any type -- "the disc you inserted is not readable by this computer." Running 10.5.6 on an Imac core duo purchased August 2006. Data CDs, DVDs work fine. Have googled this subject endlessly without answer -- Imac is out of warranty and pissed off Apple want to charge me for tech support! Grateful for any help or advice. Thanks!

[DeltaMac]

Try cleaning your drive. Use a commercial DVD cleaner disk that is sold for that purpose.
If you still can't read any audio CDs, and other types of disks work, then the drive has failed (for the audio CD functions, anyway), and needs to be replaced. If you know how to get inside your iMac, then the job is not difficult. Otherwise, take to someone who knows how to do this.