Quick Reply hangs in Firefox

[Jon12345]

When someone uses Quick Reply on my site, it hangs with the screen going blank. It works fine in IE7. I think it might be something to do with some adsense code causing a problem with Ajax or something!

I have my adsense display after the first post and after the last post.

The last part of my postbit code is as follows:

<if condition="$post['islastshown'] AND !$vbulletin->GPC['ajax']">

$spacer_open
<div style="padding:0px 0px $stylevar[cellpadding]px 0px">

<table class="tborder" cellpadding="$stylevar[cellpadding]" cellspacing="$stylevar[cellspacing]" border="0" width="100%" align="center">
<tr>
    <td class="thead" align="left">Sponsored Links</td>
</tr>
<tr>
    <td class="alt1" align="center">


<script type="text/javascript"><!--
google_ad_client = "pub-xxxxxxxx";
/* Forum Posts */
google_ad_slot = "xxxxxx";
google_ad_width = xxx;
google_ad_height = xx;
//-->
</script>
<script type="text/javascript"
src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script>

    </td>
</tr>
</table>

</div>
$spacer_close

</if>

Any idea why it hangs and what I need to modify to prevent it? Do I edit the code here somehow?

Thanks,

Jon