Hi,

Got 2 domains, Domain A which is a windows 2000 native domain and Domain B which is a windows 2003 native domain, both domains are in seperate forests. There is an external selective trust setup so that Domain B can selectively trust users in Domain A and allow access to specific servers in Domain B using groups and the Authentication Allow attribute. 

Users in Domain A can access the main intranet page in Domain B as it is configured to allow anonymous authentication. However there is a link on this said intranet page in Domain B which accesses another web page. This has been configured to use Windows Integrated Authentication and users in Domain A just get presented with a blank page with no error messages when they click on this link. They can get access if they add the site as a trusted local intranet site and logon with credentials from Domain B but cannot access this page with their own credentials from Domain A.They can also access the page if anonymous authentication is selected.I have discovered that Integrated Windows authentication does not work over HTTP proxy connections but even when the page is excluded from the proxy it still doesn't work. All the permissions are setup correctly as far as i can see.

 Can this be related to the functional levels of the domains? Struggling with this, any help appreciated.

All,

Eventually resolved this. The webpage had been developed only to recognise user credentials of a particular size which was fine for users in Domain B but users in Domain A had longer user names so the webpage did not like it. This part of the webpage was not programmed to return an error code either!!