Although is it good practive to correct HTML Validation errors, it will not help in this case; is it a logic error as opposed to a syntax error.

<!--eof-navigation display-->
<!--bof-branding display-->
<div id="logoWrapper" class="clearfix">


Change it to read:

<!--eof-navigation display-->
<!--bof-branding display-->

<br class="clearBoth" />

<div id="logoWrapper" class="clearfix">


The file to edit (I'm guessing here) would be:
includes/templates/cherry_zen/common/tpl_header.php