UIloader not completely unloading (music)

I have an application that calls external SWF files through the UILoader component. I do this so I can keep the file size smaller in the beginning and only load objects as the user needs. (if there is a better way to do this, please let me know).

Here is my problem. One of the objects plays music. In it’s simplest form something like this:

var sound:Sound;
sound = new Sound( );
sound.load(new URLRequest(“fightsong.mp3”));
sound.play();

From the first application, I load the second application and the music starts playing. However, when I unload the second application the music continues to play. The applications can not talk to each other (I assume) because it is basically one SWF calling another SWF via the UILoader.

In my first application, when the uiloader is closed I have:
theLoader.unload();

however the music continues to play. Any suggestions? Can the two SWFs communicate with each other? Is there an eventlistener for exiting? or is there a better way to handle this all together?

Thank You!