Hvorfor hopper menuen?

Hej Alle,

Jeg kan simplethen ikke finde ud af hvorfor min menu hopper når der kommer en undermenu på et af hovedpunkterne..

Håber der er nogen der kan hjælpe - CSS og HTML nedenfor.. Håber det bare er noget i CSS jeg kan indstille så den ikke hopper?

CSS
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/* List TopNav Multimenu start*/

div#mainmenu  {
/* needed to give a margin above and below the buttons */

}


.mainmenu {
}
#nav {
    list-style: none;
    position: relative;

    color : #344760;
    font-weight : bold;
    font-family :  arial , sans-serif;
    font-size:16px;
    text-decoration : none;
    width: 150px;
    margin: 10px 10px 10px 10px;
    text-align : right;
    height:22px;
    line-height:22px;   
}

#nav ul {
    list-style: none;
    display: none;
    position: absolute;
    overflow: visible;
}

#nav li {
    display: block;
    position: relative;
   
    color : #344760;
    font-weight : bold;
    font-family :  arial , sans-serif;
    font-size:16px;
    text-decoration : none;
      width: 150px;
    text-align : right;
    height:22px;
    line-height:22px;
}

#nav li a {
    display: block;
    color : #344760; 
    font-weight: bold;
    text-decoration: none;
        height:22px;
    line-height:22px;
}

#nav li a:hover {
    color : #344760;
    background:#FFFFFF;
        height:22px;
    line-height:22px;
}

#nav li#sel A {
    color : #344760;
        height:22px;
    line-height:22px;
}
#nav li#sel A:hover {
    color: #773106;
        height:22px;
    line-height:22px;
}

/* 1st dropdown level */
#level1 {
    display: block;
    left: 138px;
    top: 0; !important;
    margin: 0px 10px 0px 10px;
    font-size: 12px;
    font-family: arial;
    font-weight: bold;
    height:12px;
    line-height:12px;
}
#level1 UL {
    position: relativ;
    overflow: visible;
}
#level1 li {
    display: block;
    margin: 0 !important; 
    margin: 0;
    padding: -0 0 !important;
    font-size: 12px;
    height:12px;
    line-height:12px;
}
#level1 li A {
    display: block;
    width: 150px;
    background: #344760;
    padding: 2px;
    font-weight: normal;
    text-align: left;
    text-decoration: none;
    color: #FFFFFF;
    margin: 0px 10px 0px 10px;
    border: 0;
    height:12px;
    line-height:12px;
}
#level1 li A:hover {
    display: block;
    color: #344760;
    background-color: #FFFFFF;
    height:12px;
    line-height:12px;
}

#level1 li#sel A {
    background-color: #344760;
    color: #FFFFFF;
    height:12px;
    line-height:12px;
}
#level1 li#sel A:hover {
    background-color: #344760;
    color: #FFFFFF;
    height:12px;
    line-height:12px;
}
------------------------

HTML
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<td id="mainmenu"><UL id=nav><LI><a href="index.php?id=2" title="Forsiden" onfocus="blurLink(this);">Forsiden</a></LI><LI id=sel><a href="index.php?id=3" title="Profil" onfocus="blurLink(this);">Profil</a><UL id=level1><LI><a href="index.php?id=18" title="Profil (fortsat)" onfocus="blurLink(this);">Profil (fortsat)</a></LI></UL></LI><LI><a href="index.php?id=4" title="Kunsten" onfocus="blurLink(this);">Kunsten</a></LI><LI><a href="index.php?id=5" title="Musikken" onfocus="blurLink(this);">Musikken</a><UL id=level1><LI><a href="index.php?id=21" title="Musikken (fortsat)" onfocus="blurLink(this);">Musikken (fortsat)</a></LI></UL></LI><LI><a href="index.php?id=17" title="Netop nu!" onfocus="blurLink(this);">Netop nu!</a></LI><LI><a href="index.php?id=7" title="Galleri" onfocus="blurLink(this);">Galleri</a></LI><LI><a href="index.php?id=9" title="Kontakt" onfocus="blurLink(this);">Kontakt</a></LI></UL></td>

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