HI, We are using ISA 2004 as proxy server in our organisation and it is associated to corporate AD. The user authentication works fine and they are able to browse properly, but when we use any application which need to connect to internet and get some updates or information it does not work. In the application Proxy settings TAb we provide Proxy Address, Port details and user credentials which have access to internet. When we try to update it fails with error code 407 which states that Proxy authentication is required. Why do we face this kind of issue, do we have to do some changes on AD or ISA end to enable the same.

a disclaimer to start with, not using isa server myself, though maybe this blog posts gives some ideas even if its about isa 2000 http://blogs.technet.com/b/tristank/archive/2004/06/25/165457.aspx should noone here knows an answer, you can try the forefront and isa forum here: http://social.technet.microsoft.com/Forums/en-US/category/forefront