Be Careful with Group Policies....
Puff... I was in a great problem recently....
We have Microsoft Dynamics CRM 2011 deployment over here, which stopped working unexpectedly and started to throw, when trying to access it using URL, error which said:
Business Management Error
"You are attempting to create a user with a domain logon that does not exist."
Secondly I noticed, that some of users were having problems of Trust relationship with the domain. We have only one Domain Controller.
The Third thing I found was the error while updating Group Policies.
Whenever I used gpupdate /force to update policies on workstation I would get: