Broken Ad on the right of forum

[spinko]

I recently updated from vb3 to vb4. Since then, we have had some challenges with posts when an ad that I "jimmied" on to the right side of the forum is in place. The forum becomes extremely wide. It only persists when only specific circumstances are met:

1) It's only affected on IE 7 or older (or 8 and up with compatibility mode on), FF and chrome are fine.
2) It's only in an actual post, all other pages are fine.
3) You have to be logged in to see it. When you're logged out, it's fine.

In the header template, I have the following:

At the very bottom:

<!--Side advert -->
<table width="100%" border="0" cellpadding="5" cellspacing="5" align="center" style="padding: $stylevar[cellpadding]px;" class="page">
        <tbody>
	<tr>
	<td valign="top">

<!--end side advert -->

In the footer Template:

After:

{vb:raw ad_location.ad_footer_start}
{vb:raw ad_location.global_above_footer}
<div id="footer" class="floatcontainer footer">

I have:

<!-- side ad -->
</td><td width="100" valign="top"><a href='http://rapp.bc.ca/' target='_blank'><img src='http://www.huntingbc.ca/adverts/RAPPlogo100x128.gif' border='0'></a>

	</td>
	</tr>
</tbody>
</table>
<!-- /side ad -->

Thoughts? It seems like as soon as I put a table there it gets goofy. Any suggestions would be fantastic.