Hi Admin,

I notice the lightbox, is set to open post attachments in a new window, (well it does for me with firefox 3.6.11 anyway)

Having recently installed vbulletin (3.8.6) and despite many attempts to get the lightbox working for post attachments I eventually gave up on the vbulletin lightbox.. and looked around for alternatives for displaying thumbnails..

The only one that worked reliably (for me at least) was slimbox, from here
Slimbox 2, the ultimate lightweight Lightbox clone for jQuery · digitalia.be

You can see it running here..
Slimbox Lightbox test - Saw Discussion Forums

The only template changes were in headerinclude

Code:
<script type="text/javascript" src="http://www.backsaw.net/forum/js/jquery.js"></script>
<script type="text/javascript" src="slimbox/js/slimbox2.js"></script>
<link rel="stylesheet" href="slimbox/css/slimbox2.css" type="text/css" media="screen" />
And in postbit_attachmentthumbnail

Code:
    <a href="attachment.php?attachmentid=&amp;d=" 
        rel="lightbox-cat" id="attachment" title=""
        target="_blank"
     >
Have a look at it if you are going to play with the lightbox in the future.

Regards
Ray