Crossdomain.xml - This is my guess at what this xml does.  Don't take my word for any of this :-).  Crossdomain.xml gives web applications access to files from one domain (ie: server) to another domain (ie: server) within a specific web page.  So an web page on one server can access content on another server.  This added security seemed to be introduced with IE 7 if I remember correctly. 


Create a file called: crossdomain.xml
Place this file in the webroot of the server.  (IIS ex: C:\inetpub\wwwroot)
The following XML code will give full access to the servers just like before the new security was added to IE.

<?xml version="1.0"?>
<!DOCTYPE cross-domain-policy SYSTEM "">
<allow-access-from domain="*" />