I have validated my html, php and css from W3C on the website I am currently working on.

I have found that implementing the Son of Suckerfish dropdown menu works well in Firefox, but not at all in IE. I believe the javascript from the sfHover.js file is causing this pageload error in IE:
Code:
Line: 3
Char: 2
Error: 'document.getElementByld(...)' is null or not an object
Code: 0
URL:http://www.umedplans.com/index2.php
If I comment out the call for it in the header of my webpage, no error occurs. I have recopied and pasted from the above link several times to make sure I didn't mess the code up accidentally, and I am sure it is clean. Here is the javascript from Son of Suckerfish:
Code:
sfHover = function() {
	var sfEls = document.getElementById("nav").getElementsByTagName("LI");
	for (var i=0; i<sfEls.length; i++) {
		sfEls[i].onmouseover=function() {
			this.className+=" sfhover";
		}
		sfEls[i].onmouseout=function() {
			this.className=this.className.replace(new RegExp(" sfhover\\b"), "");
		}
	}
}

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

Does anyone have any ideas why this is doing this or how to fix it?