Could you paste your 'forumdisplay_thread' template here?
Line 2 of that template should look similar to this:
<td align="center" class="{$bgcolor}{$thread_type_class}" width="2%"><img src="{$theme['imgdir']}/{$folder}.gif" alt="{$folder_label}" title="{$folder_label}" /></td>
If it's different, try replacing the entire line with that code and see if it fixes things.
This is what my forumdisplay_thread looks like:
<tr>
<td align="center" class="forumdisplay_trow {$thread_type_class}" width="2%">{$folders}</td>
<td class="forumdisplay_trow_hover {$thread_type_class}">
{$attachment_count}
<div>
<span>{$prefix} {$gotounread}{$thread['threadprefix']}<a href="{$thread['threadlink']}" class="{$inline_edit_class} {$new_class}" id="tid_{$inline_edit_tid}">{$thread['subject']}</a>{$thread['multipage']}</span>
<div class="author smalltext">{$thread['profilelink']}</div>
</div>
</td>
<td align="center" class="forumdisplay_trow2 {$thread_type_class}"><a href="javascript:MyBB.whoPosted({$thread['tid']});">{$thread['replies']}</a>{$unapproved_posts}</td>
<td align="center" class="forumdisplay_trow {$thread_type_class}">{$thread['profilelink']}</td>
<td align="center" class="forumdisplay_trow2 {$thread_type_class}">{$thread['views']}</td>
<td class="forumdisplay_trow {$thread_type_class}" style="white-space: nowrap; text-align: right;">
<span class="lastpost smalltext">{$lastpostdate} {$lastposttime}<br />
<a href="{$thread['lastpostlink']}">{$lang->lastpost}</a>: {$lastposterlink}</span>
</td>
{$modbit}
</tr>
I managed to get the icon back on the page but it was all messed up
Anyone know the solution?