Xml player help

Please help! Im new to flash and have made my first website with help from a mixture of tuts. I have a music page on which i have placed a premade mp3 player-this works well and plays automatically when a user goes to the page. Unfortunately it continues playing after you have left the page and if you return to the page starts again so you have multiple mp3’s playing. Can anybody tell me how to stop this. Heres the mp3 player action script which is embedded inside the mp3 player.

volume_mc.slider_mc.useHandCursor = true;

var musicReq:URLRequest;
var music:Sound = new Sound();
var sc:SoundChannel;
var currentSound:Sound = music;
var pos:Number;
var songPlaying:Boolean = false;

var xml:XML;
var songlist:XMLList;
var currentIndex:Number = 0;

var loader:URLLoader = new URLLoader();
loader.addEventListener(Event.COMPLETE, whenLoaded);

function whenLoaded(e:Event):void
{
xml = new XML(e.target.data);
songlist = xml.song;
musicReq = new URLRequest(songlist[0].url);
music.load(musicReq);
sc = music.play();
title_txt.text = songlist[0].title;
artist_txt.text = songlist[0].artist;
sc.addEventListener(Event.SOUND_COMPLETE, nextSong);
}

loader.load(new URLRequest(“jukebox.xml”));

next_btn.addEventListener(MouseEvent.CLICK, nextSong);
prev_btn.addEventListener(MouseEvent.CLICK, prevSong);
pause_btn.addEventListener(MouseEvent.CLICK,pauseSong);

stop_btn.addEventListener(MouseEvent.CLICK,stopSong);

function nextSong(e:Event):void
{
if (currentIndex < (songlist.length() - 1))
{
currentIndex++;
}
else
{
currentIndex = 0;
}

var nextReq:URLRequest = new URLRequest(songlist[currentIndex].url);
var nextTitle:Sound = new Sound(nextReq);
sc.stop();
title_txt.text = songlist[currentIndex].title;
artist_txt.text = songlist[currentIndex].artist;
sc = nextTitle.play();
songPlaying = true;
currentSound = nextTitle;
sc.addEventListener(Event.SOUND_COMPLETE, nextSong);

}

function prevSong(e:Event):void
{
if (currentIndex > 0)
{
currentIndex–;
}
else
{
currentIndex = songlist.length() - 1;
}

var nextReq:URLRequest = new URLRequest(songlist[currentIndex].url);
var prevTitle:Sound = new Sound(nextReq);
sc.stop();
title_txt.text = songlist[currentIndex].title;
artist_txt.text = songlist[currentIndex].artist;
sc = prevTitle.play();
songPlaying = true;
currentSound = prevTitle;
sc.addEventListener(Event.SOUND_COMPLETE, nextSong);

}

function pauseSong(e:Event):void
{
pos = sc.position;
sc.stop();
songPlaying = false;
play_btn.addEventListener(MouseEvent.CLICK,playSong);
}

function playSong(e:Event):void
{
if(songPlaying == false)
{
sc = currentSound.play(pos);
sc.addEventListener(Event.SOUND_COMPLETE, nextSong);
songPlaying = true;
play_btn.removeEventListener(MouseEvent.CLICK,playSong);
}
}

function stopSong(e:Event):void
{
sc.stop();
pos = 0;
songPlaying = false;
play_btn.addEventListener(MouseEvent.CLICK,playSong);
}

//----VOLUME----//
var dragging:Boolean = false;
var rect:Rectangle = new Rectangle(0,0,50,0);
volume_mc.slider_mc.addEventListener(MouseEvent.MOUSE_DOWN,dragIt);
volume_mc.slider_mc.addEventListener(MouseEvent.MOUSE_UP,dropIt);
stage.addEventListener(MouseEvent.MOUSE_UP,dropIt);

function dragIt(e:Event):void
{
dragging = true;
e.target.startDrag(false,rect);
e.target.addEventListener(MouseEvent.MOUSE_MOVE, adjustVolume);
}

function dropIt(e:Event):void
{
if (dragging)
{
var vol:Number = volume_mc.slider_mc.x * .02;
var st:SoundTransform = new SoundTransform(vol,0);
sc.soundTransform = st;
volume_mc.slider_mc.stopDrag();
volume_mc.slider_mc.removeEventListener(MouseEvent.MOUSE_MOVE, adjustVolume);
dragging = false;
}
}

function adjustVolume(e:Event):void
{
var vol:Number = volume_mc.slider_mc.x * .02;
var st:SoundTransform = new SoundTransform(vol,0);
sc.soundTransform = st;
}

sof_mc.addEventListener(MouseEvent.CLICK, playAd);

function playAd(e:Event):void
{
ad_mc.play();
}