I have a site on A.com and an iframe on B.com which calls javascript from A.com. This works great in FF. In IE7 / 8 I am getting a
Message: Access is denied
If both the pages are under your control (i.e. they belong to you and you cn alter the code), try this -
http://www.tomhoppe.com/index.php/2008/03/cross-sub-domain-javascript-ajax-iframe-etc/
Set document.domain like this: