Sorry Bitman couldn't resist! But on the serious side, did you take the batteries out of the motion sensor for one night and see what happens? If it does come on then I would have to imagine that
1. Someone else is using x10 in the house next to you.
2. Something in your AHP and the CM15 is causing it. Clear the cm15 and reload
3. You have another motion sensor that your not aware of. In a box or something.
4. Also check your deleted files. I could have sworn that I deleted a module and until i deleted it completely it came on. But i'm not for sure on that one though.
If it doesn't come on then try a different motion sensor.
hope this helps bitman!
after that you do need an x10 exorcist. Here is the number of one I use often and recommend.
1-800-HAMMER