I know you theme is still under development. I tried XHTML 1.0 Strict validation at http://d-theme.com/aeon5 and found an error. Spans cannot contain HTML structures. Change the span to a division.

<span id="primarylinks"><ul class="links"><li class="menu-179 first"><a href="/0-9" title="0-9">0-9</a></li>
</ul></span>