saque los tr y aun nada .. , les dejo el codigo haber si me echan una manito:
<script type="text/javascript">
<!--
var spinner=null;
function prostats_reload()
{
	if(spinner){return false;}
	this.spinner = new ActivityIndicator("body", {image: "images/spinner_big.gif"});
	new Ajax.Request('xmlhttp.php?action=prostats_reload&my_post_key='+my_post_key, {method: 'post',postBody:"", onComplete:prostats_done});
	return false;
}
function prostats_done(request)
{
	if(this.spinner)
	{
		this.spinner.destroy();
		this.spinner = '';
	}
	if(request.responseText.match(/<error>(.*)<\/error>/))
	{
		message = request.responseText.match(/<error>(.*)<\/error>/);
		alert(message[1]);
	}
	else if(request.responseText)
	{
		$("prostats_table").innerHTML = request.responseText;
	}
}
-->
</script>
		<div id="prostats_table">		
                
		<table width="100%" border="0" cellspacing="{$theme[borderwidth]}" cellpadding="0" class="tborder">
<tr><td colspan="{$num_columns}">
			<table border="0" cellspacing="0" cellpadding="{$theme[tablespace]}" width="100%">
<tr><td class="thead">
			<td><strong>{$lang->prostats_prostats}</strong></td>
			<td style="text-align:{$ps_ralign};"><a href="" onclick="return prostats_reload();">{$lang->prostats_reload} <img src="{$mybb->settings['bburl']}/images/prostats/ps_reload.gif" style="vertical-align:middle;" alt="" /></a></td>
                </td></tr>
			</table>
		</tr>
                </td>
		<tbody>
		{$trow_message_top}
		<tr valign="top">
		{$prostats_content}
		</tr>
		{$trow_message_down}
		</tbody>
		</table>
		<br />
		</div>