Maybe try something like this...
Code:
var loadingCall = setInterval(preloadSite, 50);
function preloadSite() {
	var siteLoaded = _root.getBytesLoaded();
	var siteTotal = _root.getBytesTotal();
	_root.percentage = Math.round(siteLoaded/siteTotal*100);
	percentDisplay = _root.percentage+"%";
	bytesDisplay.text = "loaded "+siteLoaded+" of "+siteTotal+" bytes";
	if (siteLoaded>=siteTotal) {
		clearInterval(loadingCall);
	}
	trace(_root.percentage+" percent");
	if (_root.percentage>=100) {
		trace("percentage = 100");
	}
}