Проблема как выяснилось именно в делегировании.
http://support.microsoft.com/default.aspx?scid=kb;en-us;810572
microsoftConfigure Active Directory for Delegation
Delegation must be enabled on all computers with delegate credentials. It can be configured in the Active Directory tools.
For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
325894 How to configure computer accounts and user accounts so that they are trusted for delegation in Windows Server 2003 Enterprise Edition
The core IIS process, InetInfo.exe, is a service that runs under the LocalSystem account, and is the process that does the following: • Takes the client request
• Impersonates the user
• Performs the appropriate tasks
• Reverts to the process identity. This is LocalSystem
If you are running InetInfo.exe under an account that is different from LocalSystem, you must verify that the account is permitted to act as a delegate. In this case, do not configure the computer for delegation. 
