Hm. Based on the behavior... I wonder if the behavior you're seeing is (as was suggested earlier in the thread) that these are copy-protected CDs, designed to play on audio CD players but refusing to fully play on computer CD drives.
Were all of the audiobooks from the same publisher and the same series?
A single audiobook, 9 disks, averaging 18 files per disk, every disk showed same behavior.
I used the one computer here in the office that would read the "over-filled" tracks to rip just the final 5 tracks from each CD to MP3, using Windows Media Player's 128 fixed bit rate

and I'll use EAC/LAME to do all the rest of the tracks and then put them all together on a single MP3 CD.
I don't think it was anything as deliberate as copy protection. I think they were just trying to save 15 cents on every $49 set by cramming 9 hours of audio onto 8 CDs.
tanstaafl.