Bei hinzufügen von runden Div-Ecken fehler im ie7 durch border

[steffen]

Sooo,

also neues Html sieht so aus:

<div id="navigationDiv">  
   <ul id="navigation">  
    <li class="menuPlaceholder" id="menuPlaceholder1"> </li>  
     <li class="menuPlaceholder"></li>  
    <li class="menuTabs" id="menuTab1"><span><a>Start</a></span></li>  
     <li class="menuPlaceholder"></li>  
    <li class="menuTabs" id="menuTab2"><span id="current"><a>Team</a></span></li>  
     <li class="menuPlaceholder"></li>  
    <li class="menuTabs" id="menuTab3"><span><a>Anfahrt</a></span></li>  
     <li class="menuPlaceholder"></li>  
    <li class="menuTabs" id="menuTab4"><span><a>Angebote</a></span></li>  
     <li class="menuPlaceholder"></li>  
    <li class="menuTabs" id="menuTab5"><span><a>Kontakt</a></span></li>  
    <li class="menuPlaceholder" id="menuPlaceholderLast"></li>  
   </ul>  
   <div id="navigationLineDiv1"></div>  
   </div>

css:

#navigationDiv {  
 margin: 0 auto;  
 width: 860px;  
 background: url(images/mainDivShadow.gif);  
 padding-top: 25px;  
 }  
  
#navigation {  
 list-style: none;  
  margin: 0;  
  padding: 0;  
 }  
  
.menuTabs {  
 border: 1px solid #999;  
 float:left;  
 height: 18px;  
 font-weight: bold;  
 font-size:1.1em;  
 color: #777;  
 background: url(images/tabBackground.gif) repeat-x;  
 }  
  
.menuPlaceholder {  
 width: 2px;  
 float: left;  
 height: 18px;  
 background: url(images/menuPlaceholderBackground.gif);  
 }  
  
#menuPlaceholder1 {  
 width: 3px;  
 background: transparent;  
 }  
  
#menuPlaceholderLast {  
 width: 409px;  
 }  
  
.menuTabs span{display: block;}  
  
/* Animation */  
.menuTabs span:hover {  
 color:#427bd6;  
 cursor: default;  
 }  
  
#current{  
 background: url(images/tabBackgroundActive.gif) repeat-x bottom;  
 border-bottom: 2px solid #cfcfcf;  
 color: #427bd6;  
 margin-top: 0px;  
 }  
/* Animation End */  
  
#menuTab1{width:75px;}  
#menuTab2{width:75px;}  
#menuTab3{width:90px;}  
#menuTab4{width:95px;}  
#menuTab5{width:90px;}  
#menuTab6{width:90px;}  
  
#navigationLineDiv1 {  
 margin: auto;  
 font-size: 0pt;  
 height: 2px;  
 width: 854px;  
 background: #cfcfcf;  
 clear: left;  
 }

Die runden ecken werden trotzdem noch nicht angezeigt (im ie7)

Danke und viele Grüße
Steffen