Navigation vesrchiebt sich im IE stufenartig

<div id="mainnav">
    <div class="moduletable_menu">
	<ul class="menu">
                 <li class="active item1"><a href="http://versuch.lange-laeufer.de/"><span>Startseite</span></a></li>
                 <li class="item2"><a href="/index.php/laeufe.html"><span>Läufe</span></a></li>
                 <li class="item3"><a href="/index.php/freunde.html"><span>Freunde</span></a></li>
                 <li class="item6"><a href="/index.php/sponsoren.html"><span>Sponsoren</span></a></li>
                 <li class="item7"><a href="/index.php/presse.html"><span>Presse</span></a></li>
                 <li class="item8"><a href="/index.php/gaestebuch.html"><span>Gästebuch</span></a></li>
                 <li class="item11"><a href="/index.php/eintrag.html"><span>Eintrag</span></a></li>
                 <li class="item9"><a href="/index.php/impressum.html"><span>Impressum</span></a></li>
                 <li class="item10"><a href="/index.php/endorfer.html"><img src="/images/stories/endorfer.jpg" alt="" /><span>Endorfer für Endorfer</span></a></li>
         </ul>		
    </div>
</div>

.moduletable_menu ul {
   list-style-type: none;
    }




.moduletable_menu ul a {
   display: block;
   height: 25px; 
   line-height: 25px;
   margin-top: 4px;
   text-decoration: none;
   color: white;
   border-right:1px solid #000000;
   float: left;
   padding-left: 7px;
   padding-right: 7px;
    }






.moduletable_menu ul a:hover {
   display: block;
   height: 25px; 
   line-height: 25px;
   background-color: #000000;
   text-decoration: none;
   color: #ED7F0F;
   border-right: 1px solid #000000;
   float: left;
   margin-top: 4px;
   padding-left: 7px;
   padding-right: 7px;
    }




.moduletable_menu ul a:hover, a:active {
   display: block;
   height: 25px; 
   line-height: 25px;
   background-color: #000000;
   text-decoration: none;
   color: #ED7F0F;
   border-right: 1px solid #000000;
   float: left;
   margin-top: 4px;
   padding-left: 7px;
   padding-right: 7px;
    }