What you pasted is content code, but you forgot about header code:
Code:
<thead>
<tr>
<td class="tcat" colspan="0">
<a href="#top" onclick="return toggle_collapse('module_20')" style="float:right"><img alt="" border="0" id="collapseimg_module_20" src="http://www.occupational-hazard.com/hazard/images/buttons/collapse_tcat.gif" /></a>
<span class="smallfont"><strong>» Raid Progression</strong></span></td>
</tr>
</thead>
that's where error is: colspan="0". It should be colspan="2" for raid progression box and colspan="3" for recruitment.
Looks like Firefox is incorrectly handling bugs in that code, IE and Opera show it correctly (by completely ignoring colspan as it has invalid value).