I'm having the same problem over my LAN too. All drives are shared read only so someone can't screw with the files on another computer but can access and even copy them except music CDs. When opened, they look just like music tracks, but the full data isn't being shown. The tracks only have about 1/1000 of the expected data like I was just looking at the labeling data for the tracks. Even tried to copy them to my HD from the other computer's CD-ROM. No go as the track only was like 44kb when finished. Next I'll try to create a wav file on the other comp's HD and see if I can play that over the LAN.
Edit: I can't play even my local CD-ROM drive through the LAN explorer menu but I can directly by opening my desktop CD-ROM shortcut, highlighting tracks, and selecting 'play with winamp' (the default player).