¿Alguna de idea de mi problema?

Parece ser que tu problema no esta en la plantilla que dijeron, sino en la forumbit_depth2_forum

Tienes un td repetido, el cual esta haciendo que haya una columna del encabezado demás.

En esa plantilla, busca un td que diga algo asi:

<td class="tcat" width="2%">

Seleccionalo hasta donde termina ese td y guarda el cambio, no se que haya de por medio pero si me parece que se repite.

Si es posible pon esa plantilla aqui para editarla si necesitas ayuda o quieres asegurar el cambio.

forumbit_depth2_forum

<tr>
<td class="{$bgcolor}" align="center" valign="top" width="1"><img src="Forum_Icons/{$forum['icon']}" alt="{$forum['name']}" /></td>
<td class="{$bgcolor}" valign="top">
<strong><img src="{$theme['imgdir']}/{$lightbulb['folder']}.png" alt="{$lightbulb['altonoff']}" title="{$lightbulb['altonoff']}" class="ajax_mark_read" id="mark_read_{$forum['fid']}" /><a href="{$forum_url}">{$forum['name']}</a></strong>{$forum_viewers_text}<div class="smalltext">{$forum['description']}{$modlist}{$subforums}</div>
</td>
<td class="{$bgcolor}" valign="top" align="center" style="white-space: nowrap">{$threads}{$unapproved['unapproved_threads']}</td>
<td class="{$bgcolor}" valign="top" align="center" style="white-space: nowrap">{$posts}{$unapproved['unapproved_posts']}</td>
<td class="{$bgcolor}" valign="top" align="right" style="white-space: nowrap">{$lastpost}</td>
</tr>

forumbit_depth1_cat

<table border="0" cellspacing="{$theme['borderwidth']}" cellpadding="{$theme['tablespace']}" class="tborder">
<thead>
<tr>
<td class="thead" colspan="5">
<div class="expcolimage"><img src="{$theme['imgdir']}/{$expcolimage}" id="cat_{$forum['fid']}_img" class="expander" alt="{$expaltext}" title="{$expaltext}" /></div>
<div><strong><a href="{$forum_url}">{$forum['name']}</a></strong><br /><div class="smalltext">{$forum['description']}</div></div>
</td>
</tr>
</thead>
<tbody style="{$expdisplay}" id="cat_{$forum['fid']}_e">
<tr>
<td class="tcat" colspan="2"><span class="smalltext"><strong>{$lang->forumbit_forum}</strong></span></td>
<td class="tcat" width="85" align="center" style="white-space: nowrap"><span class="smalltext"><strong>{$lang->forumbit_threads}</strong></span></td>
<td class="tcat" width="85" align="center" style="white-space: nowrap"><span class="smalltext"><strong>{$lang->forumbit_posts}</strong></span></td>
<td class="tcat" width="200" align="center"><span class="smalltext"><strong>{$lang->forumbit_lastpost}</strong></span></td>
</tr>
{$sub_forums}
</tbody>
</table>
<br />

Perdon, puse forum, es el cat, pero el 2do.
forumbit_depth2_cat

forumbit_depth2_cat:

<tr>
<td class="{$bgcolor}" valign="top">
<strong><img src="{$theme['imgdir']}/{$lightbulb['folder']}.gif" alt="{$lightbulb['altonoff']}" title="{$lightbulb['altonoff']}" class="ajax_mark_read" id="mark_read_{$forum['fid']}" /><a href="{$forum_url}">{$forum['name']}</a></strong>{$forum_viewers_text}<div class="smalltext">{$forum['description']}{$subforums}</div>
</td>
<td class="{$bgcolor}" valign="top" align="center" style="white-space: nowrap">{$threads}{$unapproved['unapproved_threads']}</td>
<td class="{$bgcolor}" valign="top" align="center" style="white-space: nowrap">{$posts}{$unapproved['unapproved_posts']}</td>
<td class="{$bgcolor}" valign="top" align="right" style="white-space: nowrap">{$lastpost}</td>
</tr>

forumbit_depth1_cat:

<table border="0" cellspacing="{$theme['borderwidth']}" cellpadding="{$theme['tablespace']}" class="tborder">
<thead>
<tr>
<td class="thead" colspan="5">
<div class="expcolimage"><img src="{$theme['imgdir']}/{$expcolimage}" id="cat_{$forum['fid']}_img" class="expander" alt="{$expaltext}" title="{$expaltext}" /></div>
<div><strong><a href="{$forum_url}">{$forum['name']}</a></strong><br /><div class="smalltext">{$forum['description']}</div></div>
</td>
</tr>
</thead>
<tbody style="{$expdisplay}" id="cat_{$forum['fid']}_e">
<tr>
<td class="tcat" colspan="2"><span class="smalltext"><strong>{$lang->forumbit_forum}</strong></span></td>
<td class="tcat" width="85" align="center" style="white-space: nowrap"><span class="smalltext"><strong>{$lang->forumbit_threads}</strong></span></td>
<td class="tcat" width="85" align="center" style="white-space: nowrap"><span class="smalltext"><strong>{$lang->forumbit_posts}</strong></span></td>
<td class="tcat" width="200" align="center"><span class="smalltext"><strong>{$lang->forumbit_lastpost}</strong></span></td>
</tr>
{$sub_forums}
</tbody>
</table>
<br />

Que raro... todas esas las plantillas estan bien....

Lo ultimo que se me ocurre es en la plantilla de forumdisplay_subforums...

forumdisplay_subforums:

<table border="0" cellspacing="{$theme['borderwidth']}" cellpadding="{$theme['tablespace']}" class="tborder">
<tr>
<td class="thead" colspan="5" align="center"><strong>{$lang->sub_forums_in}</strong></td>
</tr>
<tr>
<td class="tcat" width="2%">&nbsp;</td><td class="tcat" width="2%">&nbsp;</td>
<td class="tcat" width="59%"><span class="smalltext"><strong>{$lang->forumbit_forum}</strong></span></td>
<td class="tcat" width="7%" align="center" style="white-space: nowrap"><span class="smalltext"><strong>{$lang->forumbit_threads}</strong></span></td>
<td class="tcat" width="7%" align="center" style="white-space: nowrap"><span class="smalltext"><strong>{$lang->forumbit_posts}</strong></span></td>
<td class="tcat" width="15%" align="center"><span class="smalltext"><strong>{$lang->forumbit_lastpost}</strong></span></td>
</tr>
{$forums}
</table>
<br />

forumdisplay_threadlist

forumdisplay_threadlist

forumdisplay_threadlist:

<div class="float_left">
{$multipage}
</div>
<div class="float_left">
{$newthread}
</div>
<table border="0" cellspacing="{$theme['borderwidth']}" cellpadding="{$theme['tablespace']}" class="tborder" style="clear: both;">
<tr>
<td class="thead" colspan="{$colspan}">
<div style="float: right;">
<span class="smalltext"><strong><a href="misc.php?action=markread&amp;fid={$fid}">{$lang->markforum_read}</a> | <a href="usercp2.php?action={$add_remove_subscription}subscription&amp;type=forum&amp;fid={$fid}&amp;my_post_key={$mybb->post_code}">{$add_remove_subscription_text}</a>{$clearstoredpass}</strong></span>
</div>
<div>
<strong>{$foruminfo['name']}</strong>
</div>
</td>
</tr>
<tr>
<td class="tcat" colspan="3" width="66%"><span class="smalltext"><strong><a href="{$sorturl}&amp;sortby=subject&amp;order=asc">{$lang->thread}</a> {$orderarrow['subject']} / <a href="{$sorturl}&amp;sortby=starter&amp;order=asc">{$lang->author}</a> {$orderarrow['starter']}</strong></span></td>
<td class="tcat" align="center" width="7%"><span class="smalltext"><strong><a href="{$sorturl}&amp;sortby=replies&amp;order=desc">{$lang->replies}</a> {$orderarrow['replies']}</strong></span></td>
<td class="tcat" align="center" width="7%"><span class="smalltext"><strong><a href="{$sorturl}&amp;sortby=views&amp;order=desc">{$lang->views}</a> {$orderarrow['views']}</strong></span></td>
{$ratingcol}
<td class="tcat" align="right" width="20%"><span class="smalltext"><strong><a href="{$sorturl}&amp;sortby=lastpost&amp;order=desc">{$lang->lastpost}</a> {$orderarrow['lastpost']}</strong></span></td>
{$inlinemodcol}
</tr>
{$selectall}
{$announcementlist}
{$threads}
<tr>
<td class="tfoot" align="right" colspan="{$colspan}">
<form action="forumdisplay.php" method="get">
<input type="hidden" name="selectall" value="{$allselected}" />
<input type="hidden" name="fid" value="{$fid}" />
<select name="sortby">
<option value="subject" {$sortsel['subject']}>{$lang->sort_by_subject}</option>
<option value="lastpost" {$sortsel['lastpost']}>{$lang->sort_by_lastpost}</option>
<option value="starter" {$sortsel['starter']}>{$lang->sort_by_starter}</option>
<option value="started" {$sortsel['started']}>{$lang->sort_by_started}</option>
{$ratingsort}
<option value="replies" {$sortsel['replies']}>{$lang->sort_by_replies}</option>
<option value="views" {$sortsel['views']}>{$lang->sort_by_views}</option>
</select>
<select name="order">
<option value="asc" {$ordersel['asc']}>{$lang->sort_order_asc}</option>
<option value="desc" {$ordersel['desc']}>{$lang->sort_order_desc}</option>
</select>
<select name="datecut">
<option value="1" {$datecutsel['1']}>{$lang->datelimit_1day}</option>
<option value="5" {$datecutsel['5']}>{$lang->datelimit_5days}</option>
<option value="10" {$datecutsel['10']}>{$lang->datelimit_10days}</option>
<option value="20" {$datecutsel['20']}>{$lang->datelimit_20days}</option>
<option value="50" {$datecutsel['50']}>{$lang->datelimit_50days}</option>
<option value="75" {$datecutsel['75']}>{$lang->datelimit_75days}</option>
<option value="100" {$datecutsel['100']}>{$lang->datelimit_100days}</option>
<option value="365" {$datecutsel['365']}>{$lang->datelimit_lastyear}</option>
<option value="9999" {$datecutsel['9999']}>{$lang->datelimit_beginning}</option>
</select>
{$gobutton}
</form>
</td>
</tr>
</table>
<div class="float_left">
{$multipage}
</div>
<div class="float_left" style="margin-top: 4px;">
{$newthread}
</div>
<br style="clear: both;" />
<br />
<div class="float_left">
<div class="float_left">
<dl class="thread_legend smalltext">
<dd><img src="{$theme['imgdir']}/newfolder.gif" alt="{$lang->new_thread}" title="{$lang->new_thread}" /> {$lang->new_thread}</dd>
<dd><img src="{$theme['imgdir']}/newhotfolder.gif" alt="{$lang->new_hot_thread}" title="{$lang->new_hot_thread}" /> {$lang->new_hot_thread}</dd>
<dd><img src="{$theme['imgdir']}/hotfolder.gif" alt="{$lang->hot_thread}" title="{$lang->hot_thread}" /> {$lang->hot_thread}</dd>
</dl>
</div>

<div class="float_left">
<dl class="thread_legend smalltext">
<dd><img src="{$theme['imgdir']}/folder.gif" alt="{$lang->no_new_thread}" title="{$lang->no_new_thread}" /> {$lang->no_new_thread}</dd>
<dd><img src="{$theme['imgdir']}/dot_folder.gif" alt="{$lang->posts_by_you}" title="{$lang->posts_by_you}" /> {$lang->posts_by_you}</dd>
<dd><img src="{$theme['imgdir']}/lockfolder.gif" alt="{$lang->locked_thread}" title="{$lang->locked_thread}" /> {$lang->locked_thread}</dd>
</dl>
</div>
<br style="clear: both" />
</div>

<div class="float_right" style="text-align: right;">
{$inlinemod}
{$searchforum}
{$forumjump}
</div>
<br style="clear: both" />
{$inline_edit_js}

Se supone que vos eres la mente maestra detras de tu tema.

Prueba a dejar el forumdisplay_subforums así:

<table border="0" cellspacing="{$theme['borderwidth']}" cellpadding="{$theme['tablespace']}" class="tborder">
<tr>
<td class="thead" colspan="5" align="center"><strong>{$lang->sub_forums_in}</strong></td>
</tr>
<tr>
<td class="tcat" width="2%">&nbsp;</td>
<td class="tcat" width="59%"><span class="smalltext"><strong>{$lang->forumbit_forum}</strong></span></td>
<td class="tcat" width="7%" align="center" style="white-space: nowrap"><span class="smalltext"><strong>{$lang->forumbit_threads}</strong></span></td>
<td class="tcat" width="7%" align="center" style="white-space: nowrap"><span class="smalltext"><strong>{$lang->forumbit_posts}</strong></span></td>
<td class="tcat" width="15%" align="center"><span class="smalltext"><strong>{$lang->forumbit_lastpost}</strong></span></td>
</tr>
{$forums}
</table>
<br />