Really? Hmm, pretty much every IR protocol I've seen calls for the remote control to immediately start repeating a command once the button is pressed, and to keep repeating the command until the user lets up on the button. In fact, most protocols go out of their way to tell the receiving device "the user is holding down the button right now, not pressing it repeatedly".

In fact, I have just now held the mute button down in front of my Sanyo, and the TV stayed muted rather than switching mute on and off.

The odds are good that there is a bug in my code; the protocol must not be sending the "I am repeating" code correctly. Can you tell me which keyset you were using?