Proxy asking for credentials multiple times - Authentication Problem

[Guest]

[Mo_Hong]

Hi All,
   Thanks in advance for the help.

The scenario is the following:
1. Endian Firewall 2.2rc3
2. Installed Advance ACL's to handle groups and special browsing permissions to sites
3. Created the users locally to the Endian with their assigned groups. The proxy is authenticated (obvious)
4. Created the Advance ACL's for each group/users
5. The LAN is handled by Endian. The Outgoing Firewall is in use with the required ports open.
6. The LAN has an Active Directory

The Problem is the following:
1. The user starts the browser, and the proxy asks for authentication
2. During the browsing session, the proxy asks many times for authentication
3. When the user has the Outlook open, the proxy asks for authentication, and it ask for the credentials many times.

Any clue why this behaivior with the proxy?

Regards