If the CDs themselves are physically ok and aren't scratched up, then it might be some kind of protection... I remember reading about certain CDs being manufactured by record companies in a dodgy way that prevented them from being played on computers in order to curtail pirating, but how true this is, I can't say for sure.
There's a term that was used for it, but I can't remember it. Anyway, I think you might have luck if you use a CD ripping program that can get past this. If you don't want to go through all the trouble, you can simply download the albums online at
FilesTube - Search for files on rapidshare and other download sites and use your CDs in the car or stereo.