Erro JavaScript no I.E. ("Erro em tempo de execução desconhecido")

var bustcachevar=1 //bust potential caching of external pages after initial request? (1=yes, 0=no)
var loadstatustext="<span class=red>Carregando, aguarde...</span>"

////NO NEED TO EDIT BELOW////////////////////////
var loadedobjects=""
var defaultcontentarray=new Object()
var bustcacheparameter=""

function ajaxpage(url, containerid, targetobj){
	var page_request = false
	if (window.XMLHttpRequest) // if Mozilla, Safari etc
		page_request = new XMLHttpRequest()
	else if (window.ActiveXObject){ // if IE
		try {
			page_request = new ActiveXObject("Msxml2.XMLHTTP")
		} 
		catch (e){
			try{
				page_request = new ActiveXObject("Microsoft.XMLHTTP")
			}
			catch (e){}
		}
	}
	else
		return false
		var ullist=targetobj.parentNode.parentNode.getElementsByTagName("li")
		for (var i=0; i<ullist.length; i++)
			ullist[i].className=""  //deselect all tabs
			targetobj.parentNode.className="selected"  //highlight currently clicked on tab
			if (url.indexOf("#default")!=-1){ //if simply show default content within container (verus fetch it via ajax)
				document.getElementById(containerid).innerHTML=defaultcontentarray[containerid]
				return
			}
			document.getElementById(containerid).innerHTML=loadstatustext
			page_request.onreadystatechange=function(){
			loadpage(page_request, containerid)
	}
	if (bustcachevar) //if bust caching of external page
		bustcacheparameter=(url.indexOf("?")!=-1)? "&"+new Date().getTime() : "?"+new Date().getTime()
		page_request.open('GET', url+bustcacheparameter, true)
		page_request.send(null)
	}

	function loadpage(page_request, containerid){
		if (page_request.readyState == 4 && (page_request.status==200 || window.location.href.indexOf("http")==-1))
			document.getElementById(containerid).innerHTML = unescape(page_request.responseText.replace(/\+/g," "))
	}

	function loadobjs(revattribute){
		if (revattribute!=null && revattribute!=""){ //if "rev" attribute is defined (load external .js or .css files)
			var objectlist=revattribute.split(/\s*,\s*/) //split the files and store as array
			for (var i=0; i<objectlist.length; i++){
				var file=objectlist[i]
				var fileref=""
				if (loadedobjects.indexOf(file)==-1){ //Check to see if this object has not already been added to page before proceeding
					if (file.indexOf(".js")!=-1){ //If object is a js file
						fileref=document.createElement('script')
						fileref.setAttribute("type","text/javascript");
						fileref.setAttribute("src", file);
					}
					else if (file.indexOf(".css")!=-1){ //If object is a css file
						fileref=document.createElement("link")
						fileref.setAttribute("rel", "stylesheet");
						fileref.setAttribute("type", "text/css");
						fileref.setAttribute("href", file);
					}
				}
				if (fileref!=""){
					document.getElementsByTagName("head").item(0).appendChild(fileref)
					loadedobjects+=file+" " //Remember this object as being already added to page
				}
			}
		}
	}

	function expandtab(tabcontentid, tabnumber){ //interface for selecting a tab (plus expand corresponding content)
		var thetab=document.getElementById(tabcontentid).getElementsByTagName("a")[tabnumber]
		if (thetab.getAttribute("rel")){
			ajaxpage(thetab.getAttribute("href"), thetab.getAttribute("rel"), thetab)
			loadobjs(thetab.getAttribute("rev"))
		}
	}

	function savedefaultcontent(contentid){// save default ajax tab content
		if (typeof defaultcontentarray[contentid]=="undefined") //if default content hasn't already been saved
			defaultcontentarray[contentid]=document.getElementById(contentid).innerHTML
	}

	function startajaxtabs(){
		for (var i=0; i<arguments.length; i++){ //loop through passed UL ids
			var ulobj=document.getElementById(arguments[i])
			var ulist=ulobj.getElementsByTagName("li") //array containing the LI elements within UL
			for (var x=0; x<ulist.length; x++){ //loop through each LI element
				var ulistlink=ulist[x].getElementsByTagName("a")[0]
				if (ulistlink.getAttribute("rel")){
					var modifiedurl=ulistlink.getAttribute("href").replace(/^http:\/\/[^\/]+\//i, "http://"+window.location.host+"/")
					ulistlink.setAttribute("href", modifiedurl) //replace URL's root domain with dynamic root domain, for ajax security sake
					savedefaultcontent(ulistlink.getAttribute("rel")) //save default ajax tab content
					ulistlink.onclick=function(){
					ajaxpage(this.getAttribute("href"), this.getAttribute("rel"), this)
					loadobjs(this.getAttribute("rev"))
					return false
				}
				if (ulist[x].className=="selected"){
					ajaxpage(ulistlink.getAttribute("href"), ulistlink.getAttribute("rel"), ulistlink) //auto load currenly selected tab content
					loadobjs(ulistlink.getAttribute("rev")) //auto load any accompanying .js and .css files
				}
			}
		}
	}
}