function activateDropDownMenu(){

  if(!document.getElementById("topMenu")){
   return false;
  }
	var menuelements=document.getElementById("topMenu").getElementsByTagName("LI");
	for (var i=0;i<menuelements.length;i++){
		menuelements[i].onmouseover=function(){
			this.className +=" mouseHoverIE";
		}
		menuelements[i].onmouseout=function(){
			this.className=this.className.replace(new RegExp(" mouseHoverIE\\b"), "");
		}
	}
}

if(window.attachEvent) window.attachEvent("onload",activateDropDownMenu);