Hi,
I've installed JBoss Portal and Forums. I'm using JBossAS 4.0.2 and JBoss Portal 2.0 final. My database is MySQL MaxDB (formerly SapDB), version 7.5.0.1.
The application starts up correctly, and I can see the main page, the forums and so on. The problem is when I try to login as administrator to get to the admin page. I put admin/admin as stated in the documentation, but it fails showing a blank page. This is the stack trace of the error:

10:29:39,058 ERROR [CoyoteAdapter] An exception or error occurred in the container during the request processing
java.lang.NullPointerException
 at java.lang.String.compareTo(String.java:998)
 at java.lang.String.compareTo(String.java:90)
 at java.util.Arrays.mergeSort(Arrays.java:1156)
 at java.util.Arrays.sort(Arrays.java:1080)
 at org.apache.catalina.realm.GenericPrincipal.<init>(GenericPrincipal.java:77)
 at org.jboss.web.tomcat.security.JBossGenericPrincipal.<init>(JBossGenericPrincipal.java:56)
 at org.jboss.web.tomcat.security.JBossSecurityMgrRealm.getCachingPrincpal(JBossSecurityMgrRealm.java:379)
 at org.jboss.web.tomcat.security.JBossSecurityMgrRealm.authenticate(JBossSecurityMgrRealm.java:244)
 at org.apache.catalina.authenticator.FormAuthenticator.authenticate(FormAuthenticator.java:256)
 at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:391)
 at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:59)
 at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
 at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
 at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
 at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
 at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:856)
 at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:744)
 at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
 at org.apache.tomcat.util.net.MasterSlaveWorkerThread.run(MasterSlaveWorkerThread.java:112)
 at java.lang.Thread.run(Thread.java:595)

I've also rebuilt the schemas through the JMX console, both for the core and the forums, and it worked ok (dropSchema, createSchema, createContent), but it keeps failing. I've checked that the tables are created and correctly populated.
Any clues about what is failing? I'm not new to Jboss, but I am to Jboss Portal.

Tanks,

Narciso Cerezo