Two sound vars in conflict?

hi you all,
I’ve built a click&point adventure (actually in beta version), with a lot of sounds inside. They all run well, I load them with a simple code:

var my_sound:Sound = new Sound();
my_sound.attachSound(“rumorino.wav”);
my_sound.start(0, 99);

The adventure swf is formed from a lot of different scenarios, and some of the scenes are linked in a way, some others in another way and so on. Because I don’t know in which scene the user is going from which other, I decided to start any scene with a stopAllSound in order to shut down any sonic remaining from the previous scene

Now I wish to add a general soundtrack always playing on the bottom: it’s a mp3.

I’ve made another swf and loaded it with loadMovie (or loadMovieNum, is the same) over the adventure.

Here come the problem. When I play both the swf from a base (loaded with loadMovie) or from the html, the sound seems corrupted, and sometimes I heard only the soundtrack, sometimes just the game sounds. Furthermore, this kind of problem shows from the second or the third scene, rather than from the beginning

Why? It’s a matter of stopAllSounds command?

I can’t figure it out. Pls gimme some clue
thanking you in advance