It looks like you are missing the part in your navbar that calls the javascript (the id and the script call). For instance, for search, you have:
HTML Code:
<td class="vbmenu_control"><a href="search.php">Search</a></td>
And it should be:
HTML Code:
<td id="navbar_search" class="vbmenu_control"><a href="search.php" accesskey="4" rel="nofollow">Search</a> <script type="text/javascript"> vbmenu_register("navbar_search"); </script></td>
Did you perhaps turn off vboptions > Style & Language Settings > Use 'vBMenu' DHTML Popup Menus?