Ok I'm pretty sure I'm missing something obvious, but how do I name my music in flash? I labeled it in actionscript like you said, but my music still plays. Does "blah = new Sound ();" automatically label the music? How does flash know which music file to play/stop in the button?
Oh but that's the point. You need two buttons: One with the script to turn the volume down to zero and another to turn it back up to 100. (The script for each button is identical except for the numbers '0' and '100').
The next step is combining the two into one movie symbol, but make sure you can get the two buttons working first.