I found the problem, however there seems to be an issue with flareupload right now, so here is the fix itself.
In public_forum_summary.pl, change
<a href="javascript:void(0);" onclick="hideit('$cat_number' , 'visible');"><span id="shown-$cat_number">
<img src="$vars_config{NonCGIURL}/catexpand.gif" alt="[-]" id="imgshown-$cat_number" border="0"/></span></a>
to
<a href="javascript:void(0);" onclick="hideit('$cat_number' , 'visible');"><span id="shown-$cat_number">
<img src="$vars_config{NonCGIURL}/catminimize.gif" alt="[-]" id="imgshown-$cat_number" border="0"/></span></a>