New User get 401 - Unauthorized: Access is denied

Hi All,

I am using Dynamics CRM 2011 synchronized to AD instaled on windows server 2008 R2.

I have created a new user that was recognized as existent AD user through the creation by the CRM,

Configured some security roles,

But when the user tries to log in through the windows authentication dialog, he is prompted again and again, and after 3-4 times he gets the 401 error:

HTTP Error 401 - Unauthorized: Access is denied

If I try to log in with my user or any other they all work fine.

If I use IP address of the crm site + port, to log in to CRM with the problematic user its' working!!

Thank you in advance,

Uri