BEK, i feel your pain. i have posted my share of ir543 troubles here. i am about to order another one 'cause i think this one finally gave up. my family room has a western exposure so i would get the setting sun everyday and that would cause hell with my ir543. i hope my next ir543 will be better. if not, i will have to label it as a POS. yo're lucky, my ir543 doesn't even get the signal when i transmit and i know damn well my mx500 is sending it. you are right about other remotes not having trouble. i never thought of that. well, let's see if any one else has some insight to our troubles. peace :)