Confluence becomes nonresponsive after a few seconds

When I access confluence dashboard confluence works correctly but after entering some specific's space email archive it becomes nonresponsive and I must jill the java process because bin/shutdown.sh will never finish. Before having this problem I had some out of memory errors while confluence was probably receiving emails but the error talks about session storage so I am confused about the real cause.

The log shows the following:

INFO: Starting Coyote HTTP/1.1 on http-80
Jan 18, 2007 11:24:51 PM org.apache.catalina.storeconfig.StoreLoader load
INFO: Find registry server-registry.xml at classpath resource
Jan 18, 2007 11:24:52 PM org.apache.catalina.startup.Catalina start
INFO: Server startup in 93996 ms
Jan 18, 2007 11:28:43 PM org.apache.coyote.http11.Http11BaseProtocol pause
INFO: Pausing Coyote HTTP/1.1 on http-80

Jan 18, 2007 11:28:45 PM org.apache.catalina.core.StandardService stop
INFO: Stopping service Catalina
2007-01-18 23:28:47,684 INFO [main] [com.atlassian.confluence.lifecycle] contextDestroyed Stopping Confluence
2007-01-18 23:28:48,301 WARN [main] [ContainerBase.[Catalina].[localhost].[/confluence]] writeObject Cannot serialize session attribute seraph_defaultauthenticator_user for session E431792ACDEE3E2F2B630ED7FC11249E
java.io.NotSerializableException: org.apache.log4j.Logger
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1075)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1369)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1341)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1284)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1073)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1369)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1341)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1284)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1073)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1369)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1341)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1284)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1073)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1369)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1341)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1284)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1073)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:291)
at org.apache.catalina.session.StandardSession.writeObject(StandardSession.java:1460)
at org.apache.catalina.session.StandardSession.writeObjectData(StandardSession.java:936)
at org.apache.catalina.session.StandardManager.doUnload(StandardManager.java:516)
at org.apache.catalina.session.StandardManager.unload(StandardManager.java:462)
at org.apache.catalina.session.StandardManager.stop(StandardManager.java:666)
at org.apache.catalina.core.StandardContext.stop(StandardContext.java:4316)
at org.apache.catalina.core.ContainerBase.removeChild(ContainerBase.java:892)
at org.apache.catalina.startup.HostConfig.undeployApps(HostConfig.java:1159)
at org.apache.catalina.startup.HostConfig.stop(HostConfig.java:1131)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:312)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
at org.apache.catalina.core.ContainerBase.stop(ContainerBase.java:1053)
at org.apache.catalina.core.ContainerBase.stop(ContainerBase.java:1065)
at org.apache.catalina.core.StandardEngine.stop(StandardEngine.java:447)
at org.apache.catalina.core.StandardService.stop(StandardService.java:512)
at org.apache.catalina.core.StandardServer.stop(StandardServer.java:734)
at org.apache.catalina.startup.Catalina.stop(Catalina.java:601)
at org.apache.catalina.startup.Catalina.start(Catalina.java:576)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:275)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:413)
Jan 18, 2007 11:28:48 PM org.apache.catalina.core.StandardWrapper unload
INFO: Waiting for 2 instance(s) to be deallocated
Jan 18, 2007 11:28:49 PM org.apache.catalina.core.StandardWrapper unload
INFO: Waiting for 2 instance(s) to be deallocated
Jan 18, 2007 11:28:50 PM org.apache.catalina.core.StandardWrapper unload
INFO: Waiting for 2 instance(s) to be deallocated
Jan 18, 2007 11:29:28 PM org.apache.coyote.http11.Http11BaseProtocol destroy
INFO: Stopping Coyote HTTP/1.1 on http-80
Jan 18, 2007 11:29:32 PM org.apache.catalina.loader.WebappClassLoader loadClass
INFO: Illegal access: this web application instance has been stopped already. Could not load com.tangosol.util.LiteSet$1. The eventual following stack trace is caused by an error thrown for debugging purposes as well as to attempt to terminate the thread which caused the illegal access, and has no functional impact.
java.lang.IllegalStateException
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1238)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1198)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
at com.tangosol.util.LiteSet.iterator(LiteSet.java:160)
at com.tangosol.coherence.component.util.SafeCluster.shutdownLocalServices(SafeCluster.CDB:6)
at com.tangosol.coherence.component.util.SafeCluster$ShutdownHook.run(SafeCluster.CDB:1)
at java.lang.Thread.run(Thread.java:595)