Resolved Content not visible

Hi

I just installed the Frequent theme (very nice btw) but encounter some problems.

When I click on an article I get a 500 - JHtml::Icon not supported error. After Googling a bit I found a fix for that (or maybe not).
They told to add JHtml::addIncludePath( JPATH_COMPONENT . '/helpers' ); on top of the html/com_content/article/default.php of the template.

I've done that and I can click on articles, but now my content isn't visible anymore (the menus are)

any idea what might be the cause (and fix). I run Joomla 2.5

Site: http://khzs.be

edit: renaming com_content to something else fixes it (although it doesn't look like it should), so I guess it's something in there