Mac not recognizing CDs

[jordanmichaelkr]

Over the years several proffessional photographers have documented my wife and my lives. They have given us CDs with photos on them. Recently, our MAC stopped opening these CDs. When I put them in the slot a window comes up telling me that I haqve just inserted a blank CD and how would I like to continue. These are not blank CDs. Our drive works fine. Music CDs work. Games work. DVDs work. Turbo Tax works. Just photo CDs. I'm Stymmied.

Here's my Mac info:
Hardware Overview:

Model Name: iMac
Model Identifier: iMac4,1
Processor Name: Intel Core Duo
Processor Speed: 1.83 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache (per processor): 2 MB
Memory: 512 MB
Bus Speed: 667 MHz
Boot ROM Version: IM41.0055.B08
SMC Version: 1.1f5

We're running Mac OS X, version 10.4.11