Are you using AHP also? Could it be one of your lights are also a trigger in a macro? Or maybe a signal collision?
Just a guess.
Say guys there's a really large church near by so I'm now thinking that some noise of some kind is actually coming in the house...While I'm sure there have been at least one "God..." and "Jesus" exclaimed from time to time by an X10 DIY person, I think this is the first time I've ever heard of a church being accused of interfering with X10. ;)