When you view NTFS or share permissions, no account or group information is displayed, just the SID?

You Application event log contains:

Event Type: Error                              Event Source: Userenv                              Event Category: None                              Event ID: 1000                              Description: Windows cannot determine the user or computer name. Return value (5).
If you run Gpresult.exe, you get similar results.

This problem can be caused by removing the right to Access this Computer from the Network from the Everyone and/or Authenticated Users group.

To fix the problem, insure that Administrators, Authenticated Users, and Everyone has the right to Access this Computer from the Network.

NOTE: Include the Everyone group because some operations involve accounts that have NOT been authenticated to the domain, such as when a user changes an expired password, or in dealing with trusts.

Use the appropriate GPO and navigate through Computer Configuration\Windows Settings\Security Settings\Local Policies\User Rights Assignment.