Drop Down Menu not working in IE

I am using this tutorial to make a suckerfish menu, but it doesn't work in IE7 - when you hover over the first leverl, the menu drops down, but doesn't disappear when you leave it. As it works fine on Opera, Firefox and Safari, I know this is a JavaScript issue, or maybe I missed something in the CSS.

My HTML

<ul id="nav">
	<li><a class="toplink" href="#">Home</a>
		<ul>
			<li><a href="#">Remoras</a></li>
			<li><a href="#">Tilefishes</a></li>
			<li><a href="#">Bluefishes</a></li>
			<li><a href="#">Tigerfishes</a></li>
		</ul>
	</li>

	<li><a class="toplink" href="#">Support</a>
		<ul>
			<li><a href="#">Climbing perches</a></li>
			<li><a href="#">Labyrinthfishes</a></li>
			<li><a href="#">Kissing gouramis</a></li>
			<li><a href="#">Pike-heads</a></li>
			<li><a href="#">Giant gouramis</a></li>
		</ul>
	</li>
    <li><a class="toplink" href="#">Forums</a></li>
</ul>

HTML:

My JavaScript (contained in a separate js file, and included in the header):

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);

Code (markup):

And associated CSS (have modified the default):

ul#nav
{
margin-left: auto;
margin-right: auto;
height: 30px;
width:800px;
display: block;
}

ul#nav
{
padding-top:40px;
padding-left:10px;
padding-right:10px;
}

#nav, #nav ul {
	padding: 0;
	margin:0;
	list-style: none;
	height: 30px;
}

#nav a {
	display: block;
	width: 10em;
	height:26px;
}

#nav a.toplink:hover {
	background:url(images/menubg2.png)
}

#nav li {
	float: left;
	width: 10em;
	height:30px;
	text-align:center;
	
}

#nav li ul {
    text-align:center;
	position: absolute;
	width: 10em;
	left: -999em;
}

#nav li:hover ul {
	left: auto;
}

#nav li:hover ul, #nav li.sfhover ul {
	left: auto;
}


#nav li ul li:hover a
{
color:#CC0000
}

Code (markup):

What is causing this error. I am running on localhost,

BP

 

Nevermind anymowre, I'm not gonna use it

BP