Just saw THE BUTTERFLY EFFECT yesterday, whose premise that you can't change the past, or otherwise you'll stuff it up even more, reminds me of another time-related movie, FREQUENCY, where the hero's character, using his deceased father's radioset IIRC, is somehow able to communicate with his fireman dad in the past, and saves him from OTL being killed in a fire, only to then have his mum become the target of a serial-killer. Any thoughts ?