Bug report: Zombie Users

Our server is running Wildfire (3.2.2) on Debian GNU/Linux Etch (4.0 RC1) in Java 2 Runtime Edition (1.5.0_10). We sometimes experience users, that are surely connected and are on the default “Online” presence status with the Psi (0.11b5) Client can send an receive messages but are NOT shown in either the rosters of other users of our server nor in the Client Session overview on the web admin panel.