Dan - If it is showing "receive" on those codes at the same time each day, then it is likely that *something* is happening at that time, and putting something on your powerline that looks like a valid signal (perhaps it IS a valid signal).
A few more things you might want to try (although you really can only do one of them per day):
1) plug in appliance modules on those codes, and see if they trigger (I think you were planning to do this already)
2) If they DO trigger, then try the next night with the CM15A UNPLUGGED from the wall at that time. (do it a few minutes early, and leave it out for a few extra minutes, just to be safe). See what happens. If the modules still trigger, then it doesn't sound like a bug to me at all. If they don't trigger, then try the NEXT night with it unplugged, and the third night WITH the CM15A plugged in (to confirm it really is the CM15A, and not a fluke).
Of course, with the CM15A unplugged, you won't see the Activity Monitor, so this only works if the appliance modules ARE being triggered at that time.
A few more things:
What type of modules are the ones on O1-O5?
Do you have any other timers around that time?
do you have any of the X10 floodlight units with the motion sensor?
What time is Dusk currently in your AHP Hardware configuration? (I'm guessing it is around 7:39 PM)
In your other thread, you mentioned timers set for some codes at Dusk-30 minutes. The timing lines up, which is why I suspect a rogue timer or macro.
Are there ANY modules or macros in your trash?
Did you clear the interface and re-download AFTER clearing the trash?