css? jquery? problem

[kozzleto]

Hi there! I'm new in the forum, and i promise i will help others with everything i can, but now i need a help... it's about my portfolio page. The menu of the top seems to work perfect on latest firefox, but in IE when i click on a link it dissapears.. I don't know why.. is it from the CSS or the jquery(the <li> are animated when clicked)...
Every advice is appreciated.. 10x in advance ;)
Soo here's the page and the code: http://admin.imi-teteven.com/

CSS:


span.cv {color: #C3C;}
span.work { color: #9C3;}
#menubg {
background: url(images/menubg.jpg) no-repeat top center;
width: 936px;
height: 131px;
}
#menubg ul {
margin: 0px;
position: relative;
top: 26px;
list-style: none;
}
#menubg ul li {
font-family: Tahoma, Geneva, sans-serif;
font-weight: bolder;
font-size: 18px;
margin-left: 55px;
display: inline;
text-decoration: none;
color: #FFF;
padding: 10px 22px;
}
#menubg ul li.first {
margin-left: -35px;
color: #FFF;
}
#menubg ul li.first:hover { border-bottom: #666 4px solid;}
#menubg ul li.CV {color: #C3C;}
#menubg ul li.CV:hover { border-bottom: #9C3 4px solid; }
#menubg ul li.WORK { color: #9C3;}
#menubg ul li.WORK:hover { border-bottom: #C3C 4px solid; }
#menubg ul li.CONTACT { color: #FFF;}
#menubg ul li.CONTACT:hover { border-bottom: #FFF 4px solid; }
#menubg ul li.active {border-bottom: #FFF 4px solid;}


Jquery:

$('#menubg ul li a').click(function(){
$('#menubg ul li').removeClass('active')
$(this).parent('li').hide().addClass('active').fadeIn('slow')
$(this).next('span').show();});
});