We had a Sharepoint site running on a server which was a domain controller and everything was working fine (IIS6), everyone could login using windows authentication. We've since added a new domain controller and demoted the IIS server to be a member server. Since then external users arent able to access the sharepoint site. The username/password prompt appears but it keeps re-appearing when credentials are entered. On the IIS server there are logs that show access denied (unknown username/password) against the connection attempt.
I think IIS is still trying to authenticate those users itself (rather than passing on on the request to the new domain controller).
Does anyone have any ideas how we could resolve this??