Hi Albert, I have a question that is exactly the same as you describre here.
I´m trying exact the same as you. Secure a service and use HTTP Basic Auth as mechanism, I already passed by the same cenarios that you describe above. Have you solved this issue ?
thank you,
Carlos
ArcGIS Server 10.1+ does work with basic authentication. I have just tested this and works fine. Remember to put in domain\username when prompted for credentials. However, please be aware that the credentials are encoded with Base64 encoding which is essentially sending the passwords in plain text. You should always perform this method of authentication over HTTPS.