Javascript menu behaving poorly in IE

Question

Let's get down to it...

site: www.erisdesigns.net

html:

<div id="wrapper">
<div id="header">
     <div id="nav">
     <dl class="dropdown">
      <dt id="one-ddheader" onmouseover="ddMenu('one',1)" onmouseout="ddMenu('one',-1)"><a class="menu" href="index.htm">Home</a></dt>
      <dd id="one-ddcontent" onmouseover="cancelHide('one')" onmouseout="ddMenu('one',-1)">
        <ul>
          <li><a href="clients.html">Clients</a></li>
          <li><a href="casestudies.html">Case Studies</a></li>
          <li><a href="contact.html">Contact</a></li>
        </ul>
      </dd>
    </dl>
    <dl class="dropdown">
      <dt id="two-ddheader" onmouseover="ddMenu('two',1)" onmouseout="ddMenu('two',-1)"><a class="menu" href="designmediums.html">Works</a></dt>
      <dd id="two-ddcontent" onmouseover="cancelHide('two')" onmouseout="ddMenu('two',-1)">
        <ul>
          <li><a href="outinthecloud.html">Out In the Cloud</a></li>
          <li><a href="printportfolio.html">Print Portfolio</a></li>
          <li><a href="photography.html">Photography</a></li>
        </ul>
      </dd>
   </dl>         
  </div>
  </div>

css:

#nav {
    top:65px;
    width:65%;
    margin-left:600px;
    padding:0;
    background:#999;
    text-align:center;
    list-style:none;
    position:relative;
    z-index:3;
}

.dropdown {float:left; text-align:center; font-size:14px; padding-right:5px; color:#FFF;}
.dropdown dt {width:175px; padding:8px; font-weight:bold; cursor:pointer; background:transparent;}
.dropdown dt:hover {background:transparent; color:#000;}
.dropdown dd {position:absolute; width:175px; display:none; background:transparent; z-index:200; opacity:0;}
.dropdown ul {width:175px; margin-top:23px; list-style:none;}
.dropdown li {display:inline-block; margin-left:-108px; float:left; padding-left:35px; text-align:left;}
.dropdown a, .dropdown a:active, .dropdown a:visited {display:inline-block; padding:5px 0px 10px 15px; color:#CCC; text-decoration:none; background:#999; width:175px; float:left;}
.dropdown a:hover {background:#999; color:#000;}
.dropdown a.menu {background:transparent; width:200px; float:left; text-align:left; color:#FFF;}
.dropdown a.menu:hover {color:#000}

and js:

var DDSPEED = 10;
var DDTIMER = 30;

// main function to handle the mouse events //
function ddMenu(id,d){
  var h = document.getElementById(id + '-ddheader');
  var c = document.getElementById(id + '-ddcontent');
  clearInterval(c.timer);
  if(d == 1){
    clearTimeout(h.timer);
    if(c.maxh && c.maxh <= c.offsetHeight){return}
    else if(!c.maxh){
      c.style.display = 'block';
      c.style.height = 'auto';
      c.maxh = c.offsetHeight;
      c.style.height = '0px';
    }
    c.timer = setInterval(function(){ddSlide(c,1)},DDTIMER);
  }else{
    h.timer = setTimeout(function(){ddCollapse(c)},50);
  }
}

// collapse the menu //
function ddCollapse(c){
  c.timer = setInterval(function(){ddSlide(c,-1)},DDTIMER);
}

// cancel the collapse if a user rolls over the dropdown //
function cancelHide(id){
  var h = document.getElementById(id + '-ddheader');
  var c = document.getElementById(id + '-ddcontent');
  clearTimeout(h.timer);
  clearInterval(c.timer);
  if(c.offsetHeight < c.maxh){
    c.timer = setInterval(function(){ddSlide(c,1)},DDTIMER);
  }
}

// incrementally expand/contract the dropdown and change the opacity //
function ddSlide(c,d){
  var currh = c.offsetHeight;
  var dist;
  if(d == 1){
    dist = (Math.round((c.maxh - currh) / DDSPEED));
  }else{
    dist = (Math.round(currh / DDSPEED));
  }
  if(dist <= 1 && d == 1){
    dist = 1;
  }
  c.style.height = currh + (dist * d) + 'px';
  c.style.opacity = currh / c.maxh;
  c.style.filter = 'alpha(opacity=' + (currh * 100 / c.maxh) + ')';
  if((currh < 2 && d != 1) || (currh > (c.maxh - 2) && d == 1)){
    clearInterval(c.timer);
  }
}

On mouseover In IE, the menu flashes into view, then quickly disappears, then dropsdown like it should but skewed to the right, cutting off some of the submenu...