Use SnoopDos to find out where it's failing.
Also, there's a mastering error on most of the discs that results in all the filenames being truncated to 8.3 with some CD filesystems. Make sure this isn't happening.
The disc also needs to be in the drive to play, and it must be called Q:. CacheCDFS can't handle volume names less than three characters, so just assign Q: to your CD drive as a workaround.
