IE7 hover state is bogus

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Howdy,
I have found a fishy bug in IE7 that is conflicting with my dropdown menus.

It appears that only in IE7, when you hover over the top level (ul li), the hidden sub-nav (ul li ul) is triggered to show, but when your mouse leaves the first li, the sub-nav disappears. Basically, you can't take your mouse out of the top level to get to the sub-nav, or the menu disappears.

All other browsers are fine, and you can navigate to the sub.

here is the style for the sub:

#block-menu-menu-main-nav .content ul.menu li ul {
	display:none;
	left:0 !important;
	font-family:Arial, Helvetica, sans-serif !important;
	list-style:none;
	position:absolute;
	top:30px;
	background:url(../images/dropdownBG.png) repeat ;
	padding:5px 0 0;
	margin:0;
	width:auto;
	height:auto;
}

Here is the action to unhide it:

#block-menu-menu-main-nav .content ul.menu li:hover ul {
	display: block;
	width:auto;
}