If those still don't work then start removing tags from the text... yes I know it won't work right but it will, hopefully, narrow down exactly what tag is causing the issue... for instance try just:
Code:
<div align="center" style="margin: 5px 5px 5px 5px;">
</div>
Do you still get an error? if not try:
Code:
<div align="center" style="margin: 5px 5px 5px 5px;">
<table class="tborder" cellpadding="6" cellspacing="1" border="0" width="100%">
<tr>
<td class="thead" style="text-align:center"></td>
</tr>
</table>
</div>
etc... until you find out exactly what piece of code is causing the error.
If you still get the error on even just a basic <div> </div> tag with no extras then I would look to the custom bb code immediately above this one, perhaps a quote is not closed throwing everything off... I've seen this issue cause havoc with css style sheets, never bb 's code but there's a first time for everything.