File Upload stopped working

Hello,
In the dialog for "Upload", the file uploads to my server and returns the result as seen from fiddler below. The dialog displays only the script tag and it's content as though there was an error, for example:

<script type="text/javascript">window.opener.CKEDITOR.tools.callFunction(4, 'ReqFiles','');</script>

This use to work and return the URL information to produce the link, somewhere along the line it stopped working for me and I am not sure why. There was no evidence of any errors along the way from the backend processing of the file to the client interface.

Any ideas?

------------------------------------FIDDLER
HTTP/1.1 200 OK
Server: Apache-Coyote/1.1
X-Powered-By: Servlet 2.5; JBoss-5.0/JBossWeb-2.1
Cache-Control: no-store, no-cache, must-revalidate
Cache-Control: post-check=0, pre-check=0
Content-Type: text/xml;charset=UTF-8
Content-Length: 100
Date: Thu, 08 Sep 2011 18:55:54 GMT

<script type="text/javascript">window.opener.CKEDITOR.tools.callFunction(4, 'ReqFiles','');</script>

------------------------------------FIDDLER END