Horizontal CSS Block Menu Not Right in FF

I have a nice horizontal block menu with CSS shown below that displays the 180 px wide blocks in IE, but not in FF. Is this fixable? Or am I doing something incorrect here?
Thanks

.topmenu {
	font-family: Verdana, sans-serif;
	font-style: normal;
	font-weight: bold;
	font-size: 11px;
	color: #FFFFFF;
	text-decoration: none;
	background-color: #C4C4FF;
	padding: 2px 2px 2px 8px;
	width: 181px;
	border-top: 1px solid #C4C4FF;
	border-bottom: 1px solid #C4C4FF;
	text-align: center;
	display: inline-block;
}

.topmenu:hover {
	font-family: Verdana, sans-serif;
	font-style: normal;
	font-weight: bold;
	font-size: 11px;
	color: #C4C4FF;
	text-decoration: none;
	background-color: #FFFFFF;
	padding: 2px 2px 2px 8px;
	width: 181px;
	text-align: center;
	display: inline-block;
}

Code (markup):

 

I found a solution at http://www.accessify.com/tools-and-wizards/developer-tools/list-o-matic/
Nice Tool!

Sorry for the bother - I am a newbie at CSS bigtime.

#navcontainer
{
margin: 0 0 0 0;
padding: 0;
height: 20px;
}

#navcontainer ul
{
border: 0;
margin: 0;
padding: 0;
list-style-type: none;
text-align: center;
}

#navcontainer ul li
{
display: block;
float: left;
text-align: center;
padding: 0;
margin: 0;
}

#navcontainer ul li a
{
background: #C4C4FF;
width: 190px;
height: 18px;
border-top: 1px solid #ffffff;
border-left: 1px solid #ffffff;
border-right: 1px solid #ffffff;
border-bottom: 1px solid #ffffff;
padding: 0;
margin: 0 0 0 0;
color: #ffffff;
text-decoration: none;
display: block;
text-align: center;
font-family: Verdana, Arial, Helvetica, sans-serif;
	font-size: 12px;
}

#navcontainer ul li a:hover
{
color: #C4C4FF;
background: #ffffff;
border-top: 1px solid #C4C4FF;
border-left: 1px solid #C4C4FF;
border-bottom: 1px solid #C4C4FF;
border-right: 1px solid #C4C4FF;
}

#navcontainer a:active
{
background: #c60;
color: #fff;
}

#navcontainer li#active a
{
background: #c60;
border: 1px solid #c60;
color: #fff;
}

Code (markup):

and

<div id="navcontainer">
    <ul id="navlist">
	<li><a href="index.html" title="Home Page">Home Page</a></li>
	<li><a href="index.html" title="Page 2">Menu Item 2</a></li>
	<li><a href="index.html" title="Page 3">Menu Item 3</a></li>
	<li><a href="photos.html" title="Photos">Photos</a></li>	
</ul>
</div>

Code (markup):

 

What might have happened in your old script was FF having trouble with display: inline-block. There's a mozilla-only version, which doens't work quite the same... FF3 will have this fixed, I've heard.