After users log off the sessions are not always closing. Messages are being lost as they are sent to sessions that are no longer in use. Before restart off the server, one user had 5 sessions listed. Ghost session will be show in the list of session in the admin page but will be counted. If you get a user info from the client buddy list, it will list the ghost sessions attached to the user. A user logged on and off while another logged in use watched, user that logged was shown as still logged in.
Openfire - 3.9.3
RedHat 5