startDropDown = function() {
	if (document.all&&document.getElementById) {
		if (document.body.id == "conference") {
			navRoot = document.getElementById("conferenceNav");
		} else if (document.body.id == "visitors") {
			navRoot = document.getElementById("visitorsNav");
		} else if (document.body.id == "exhibitors") {
			navRoot = document.getElementById("exhibitorsNav");
		}
		for (i=0; i<navRoot.childNodes.length; i++) {
			node = navRoot.childNodes[i];
				if (node.nodeName=="LI") {
					node.onmouseover=function() {
					this.className+=" over";
				}
					node.onmouseout=function() {
					this.className=this.className.replace(" over", "");
				}
			}
		}
	}
}