Small issue, and I mean small. The tab's that are inserted don't have properly formed.
Just edit the Tabs en vBulletin plugin added by this mod.
Find
Code:
$menucompleto = "<li $selecionado><a class='navtab' href='".$item_sublink[0]['url']."' target='".$item_sublink[0]['target']."'>".$new_title."</a>$link_submenu<li>";
and replace the final <li> with </li>
This will make it standards compliant.