Try each of the following steps in order until the issue is resolved:
  1. Log into the workstation with Local Administrator rights
  2. If the log in is successful:
    1. Add a new user name with the same security rights as the problem user
    2. If this corrects the issue, review What to consider before deleting a user name and delete the problem user name

  3. If the error still occurs, refer to How to troubleshoot login issues