Not quite understanding you, stopAllSounds(); would do exactly what it says, it will stop the sound. Perhaps if you clarify what your problem is it can be solved.
stopAllSounds() will stop all playing sounds, but any other encountered sound on timelines will be heard. It doesn't set the main volume to 0!
Have a look at http://www.kennybellew.com/ ... If you don't set up your movie to control sounds independently, then setting one sound's volume to 0, will set the main sound volume to 0.