Looks like your ul / li code is not valid. You have:
Code:
<ul id="udm" class="udm">
<li><a class="nohref">About the Center</a></li>
<ul>
<li><a href="/index.htm">Home</a>
</li>
<li><a href="/whoweare/">Who We Are</a>
</li>
<li><a href="/contact/">Contact</a>
</li>
<li><a href="/whoweare/faqs.html">FAQs</a></li>
<li><a href="/newsletter/archives.html">Newsletters</a></li>
</ul>
<li><a class="nohref">Research Portfolio</a></li>
<ul>
<li><a href="/people/">Researchers and Staff</a></li>
<li><a href="/whoweare/organization.html">Cores</a></li>
<li><a href="/research/">Projects</a></li>
<li><a href="/international/">International Research</a></li>
</ul>
<li><a class="nohref">Activities</a></li>
<ul>
<li><a href="/lectures/">Grand Rounds</a></li>
<li><a href="/publications/">Publications</a></li>
<li><a href="/training/">Training</a></li>
<li><a href="/videos/">Videos</a></li>
</ul>
</ul>
try this instead:
Code:
<ul id="udm" class="udm">
<li><a class="nohref">About the Center</a>
<ul>
<li><a href="/index.htm">Home</a>
</li>
<li><a href="/whoweare/">Who We Are</a>
</li>
<li><a href="/contact/">Contact</a>
</li>
<li><a href="/whoweare/faqs.html">FAQs</a></li>
<li><a href="/newsletter/archives.html">Newsletters</a></li>
</ul>
</li>
<li><a class="nohref">Research Portfolio</a>
<ul>
<li><a href="/people/">Researchers and Staff</a></li>
<li><a href="/whoweare/organization.html">Cores</a></li>
<li><a href="/research/">Projects</a></li>
<li><a href="/international/">International Research</a></li>
</ul>
</li>
<li><a class="nohref">Activities</a>
<ul>
<li><a href="/lectures/">Grand Rounds</a></li>
<li><a href="/publications/">Publications</a></li>
<li><a href="/training/">Training</a></li>
<li><a href="/videos/">Videos</a></li>
</ul>
</li>
</ul>