I'm sifting through your HTML and one area that firefox spots as a problem is here (near the bottom):
<img src='http://www.galacticwebdesigns.com/topsites/button.php?u=eltommyo' alt='Galacticwebdesigns's TopSites List' border='0' />
The Problem there, is that after the alt you use ' instead of ", so when you use Galacticwebdesign's (problem with ' in design's) it throws the html out of whack, so try this:
<img src='http://www.galacticwebdesigns.com/topsites/button.php?u=eltommyo' alt="Galacticwebdesigns's TopSites List" border='0' />
That's not going to fix your problem, but it's something I spotted. The same thing goes on (which is probably why firefox doesn't play it) in your javascript for the play button:
<input TYPE='BUTTON' NAME='darkplay' VALUE='Play!' OnClick='play(document.forms['form'].playlist);'>
The key to understanding this, is that in programming everything you open, you must also close. Here, you close what is opened, but before it's due time. Look at the onclick portion of the code here. You open the javascript statement with '. Then you get to the document.forms[ and you close the first ' with another '. Try this:
<input TYPE='BUTTON' NAME='darkplay' VALUE='Play!' OnClick="play(document.forms['form'].playlist);">
Now onto your play function.
function play(list)
{
if (playstate == 2) {
document.darkplayer.Play();
} else {
var snum = list.options[list.selectedIndex].value
document.darkplayer.FileName = songs[snum];
document.darkplayer.scr = songs[snum];
}
playstate = 1;
}
Ok, so if playstate is not equal to 2, then it sets snum to the song selected, set's the players filename and src properties, but uh, where does it tell the player to play again?