IMac stopped reading CDs

Imac, Dual core. OSX 10.4.11

CDs burned on this computer. A couple of days ago, some CDs wouldn't read, some would. Now none will. All worked well in the past (stored photos).

Commercial music CD reads fine.

Rebooted system, no help.

Any ideas?

Help appreciated, -Erik
--
DP Review Supporter.

'He who hesitates is not only lost - he's miles from the next Exit.'
http://www.flickr.com/ohlsonmh/