tomj,
Assuming you haven't screwed up royally somewhere, it would on the surface appear you have a defective CM15A. But before carving that conclusion into stone, try reprogramming your schedule completely from scratch, taking particular care not to make any mistakes. Here's my experience:
I purchased my CM15A shortly after it was introduced, and set right out to replicate the fairly long schedule I had been using on my old CM11A. As I was relatively unfamiliar with AHP I made a bunch of omissions and mistakes and hastened to correct them - rearranged and re-addressed modules and macros, deleted and re-created macros and timers, etc. The resulting schedule looked correct on the PC but was a disaster when downloaded - lights turned on and off at all the wrong times or not at all, modules at addresses that never appeared in the schedule turned on or off, etc.
I started over from scratch and carefully reprogrammed my schedule. By this time I was more familiar with AHP and less prone to make mistakes. Then the schedule worked pretty much the way it was intended to work (at least up to a point). This was with the very first release of AHP. Whatever bugs were responsible for my original disaster have hopefully been corrected in the more recent releases, but who knows.