I've seen an exception in error.log. Copied the text here from the web interface. Not sure if there is some problem with the packet.  If I remember correctly it was after updating to Openfire 3.4.1.

               2007.11.14 18:30:12 [org.jivesoftware.openfire.handler.PresenceUpdateHandler.process(PresenceUpdate Handler.java:162)

               ] Internal server error. Triggered by packet:

               <presence type="unavailable" from="avangel@4hul01070/phone"/>

               java.lang.NullPointerException: Domain cannot be null

               at org.xmpp.packet.JID.<init>(JID.java:259)

               at org.jivesoftware.openfire.SessionManager.getActiveSessionCount(SessionManager.j ava:891)

               at org.jivesoftware.openfire.spi.PresenceManagerImpl.userUnavailable(PresenceManag erImpl.java:226)

               at org.jivesoftware.openfire.handler.PresenceUpdateHandler.process(PresenceUpdateH andler.java:143)

               at org.jivesoftware.openfire.handler.PresenceUpdateHandler.process(PresenceUpdateH andler.java:110)

               at org.jivesoftware.openfire.handler.PresenceUpdateHandler.process(PresenceUpdateH andler.java:174)

               at org.jivesoftware.openfire.PresenceRouter.handle(PresenceRouter.java:130)

               at org.jivesoftware.openfire.PresenceRouter.route(PresenceRouter.java:67)

               at org.jivesoftware.openfire.spi.PacketRouterImpl.route(PacketRouterImpl.java:75)

               at org.jivesoftware.openfire.SessionManager$ClientSessionListener.onConnectionClos e(SessionManager.java:1115)

               at org.jivesoftware.openfire.nio.NIOConnection.notifyCloseListeners(NIOConnection. java:181)

               at org.jivesoftware.openfire.nio.NIOConnection.close(NIOConnection.java:164)

               at org.jivesoftware.openfire.nio.ConnectionHandler.sessionClosed(ConnectionHandler .java:86)

               at org.apache.mina.common.support.AbstractIoFilterChain$TailFilter.sessionClosed(A bstractIoFilterChain.java:550)

               at org.apache.mina.common.support.AbstractIoFilterChain.callNextSessionClosed(Abst ractIoFilterChain.java:269)

               at org.apache.mina.common.support.AbstractIoFilterChain.access$800(AbstractIoFilte rChain.java:53)

               at org.apache.mina.common.support.AbstractIoFilterChain$EntryImpl$1.sessionClosed( AbstractIoFilterChain.java:633)

               at org.apache.mina.filter.codec.ProtocolCodecFilter.sessionClosed(ProtocolCodecFil ter.java:259)

               at org.apache.mina.common.support.AbstractIoFilterChain.callNextSessionClosed(Abst ractIoFilterChain.java:269)

               at org.apache.mina.common.support.AbstractIoFilterChain.access$800(AbstractIoFilte rChain.java:53)

               at org.apache.mina.common.support.AbstractIoFilterChain$EntryImpl$1.sessionClosed( AbstractIoFilterChain.java:633)

               at org.apache.mina.filter.executor.ExecutorFilter.processEvent(ExecutorFilter.java :250)

               at org.apache.mina.filter.executor.ExecutorFilter$ProcessEventsRunnable.run(Execut orFilter.java:284)

               at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)

               at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)

               at java.lang.Thread.run(Unknown Source)