I found a minor XHTML error in the element skin..

Go to the Template FORUMHOME and find:
Code:
<td align="$stylevar[right]" valign="top"><a href="login.php?$session[sessionurl]do=logout&amp;logouthash=$bbuserinfo[logouthash]"  onclick="return log_out()"><phrase 1="$bbuserinfo[username]"><div class="smallfont">$vbphrase[log_out_x]</div></phrase></a></td>
Change to:
Code:
<td align="$stylevar[right]" valign="top"><div class="smallfont"><a href="login.php?$session[sessionurl]do=logout&amp;logouthash=$bbuserinfo[logouthash]"  onclick="return log_out()"><phrase 1="$bbuserinfo[username]">$vbphrase[log_out_x]</phrase></a></div></td>