Users can not authenticate using their Active Directory ID on one system. The following error message is present in the messages log:
The group included in the users.allow file cannot be found, this error be be logged every 30 seconds until the issue is resolved.
Check the group in Active Directory and make sure
1. The group exists
2. It is a Security Group not a Distribution Group
3. The "Group name (pre-Windows 2000)" name matches the group name