in the file
httpdocs/system/modules/xhtml5/XHTML5PageRegular.php

there is an error on line 278, with the IE conditional comments

Did read:
$this->Template->framework .= '<link rel="stylesheet" href="system/iefixes.css" type="text/css" media="screen" />' . "\n";

Should read:
$this->Template->framework .= '' . "\n";