ActionScript 2.0 :: [MX] Preloader Lock Up?

I'm using a preloader on my website. The preloader works fine on Internet Explorer, however when I tested it in Mozilla and on a Mac (running Netscape) there is a lockup on the preloader. The screen will just sit there and the website doesn't load. Both were running Flash Player 6 which is the version I'm aiming for. I found that if I refreshed the page the site would begin to work, but I doubt visitors to my site would do this and I don't want it to be required to get my site to work.

Heres the action script - from the first frame of my launch movie

Code:
stop();
function loadSWF(theURL, theTarget) {
loadMovie(theURL, theTarget);
loaderInterval = setInterval(loadChecker, 50);
}

[code]....

As you can see I call the loadSWF function to load menu.swf into the holder1_mc movieclip. That function then sets an interval with the loadChecker function that acts as the preloader. This is where nothing happens on some browsers (yet it works fine in IE).