Sound Continues in Internet Explorer After Disconnect

I'm trying to develop an audio chat room so I downloaded the FMS2 Sample Applications from Adobe - there doesn't seem to be anything more recent that is useful as a tutorial. Anyway, I've got a chat room up and running which is very close to what I want.

The problem I am having is that if I connect using Internet Explorer (8.0 on my PC), when I close the tab or even that instance of the browser, the sound continues to feed through to the browser, I've got to close all instances of the browser to kill the sound. I've tried it in Firefox and Safari, they both close the sound stream as soon as the tab/window closes so it's apparently a problem related to IE..

Any suggestions on how I can cure this.

My sample room can be accessed at http://www.roomtopray.net/joinroom.htm - as you can probably guess from the name, it's a room for religious groups - and I've left a music stream running permanently from one logged in user so you can see the problem.