IE7 onmouseout background block remains

I use

<!--[if lte IE 7]>
	<script type="text/javascript">
	sfHover=function(){var sfEls=document.getElementById("navigation").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);
	</script>
	<![endif]-->

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at http://tinyurl.com/2ujswr3 to make sure the white block is hidden onmouseout. But somehow it does not seem to run in IE7 or less. As soon as I have hovered on a menu item the white background appears and does not leave. Can someone tell me why?

PS Loading it for IE6 only now, but the issue of the script not working remains the same