Symptoms

1. User loses the ability to add users to specific groups. Whenever he clicks on the "Groups" link in the User Browser, it just says that the user is a member of all groups, even though they are not.
2. Unable to delete an unnamed Group

Diagnosis

SELECT *
FROM GROUPBASE
WHERE GROUPNAME IS NULL

+-------+-----------+
| ID    | GROUPNAME |
+-------+-----------+
| 12345	| (null)    |
+-------+-----------+

Cause

The GROUPBASE table has a NULL entry.

Resolution

1. Run the following query against your database:

   SELECT *
   FROM GROUPBASE
   WHERE GROUPNAME IS NULL
   

   This should return a result with a null group

1. Correct the faulty entry from you database using this query:

   UPDATE
   GROUPBASE
   SET GROUPNAME = 'name'
   WHERE GROUPNAME = <id>