Using:
JBoss 4.0.5 (JEMS Installer, EJB3 profile)
Portal 2.6.0.ALPHA1
MySQL
Fedora Core 6
Sun JDK 1.5.0_10

Problem:

java.lang.ClassCastException: org.jboss.portal.core.impl.model.portal.PortalImpl
 org.jboss.portal.core.impl.model.CustomizationManagerService.getDashboard(CustomizationManagerService.java:250)
 sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
 sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 java.lang.reflect.Method.invoke(Method.java:585)
 org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155)
 org.jboss.mx.server.Invocation.dispatch(Invocation.java:94)
 org.jboss.mx.interceptor.AbstractInterceptor.invoke(AbstractInterceptor.java:133)
 org.jboss.mx.server.Invocation.invoke(Invocation.java:88)
 org.jboss.mx.interceptor.ModelMBeanOperationInterceptor.invoke(ModelMBeanOperationInterceptor.java:142)
 org.jboss.mx.server.Invocation.invoke(Invocation.java:88)
 org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264)
 org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659)
 org.jboss.mx.util.MBeanProxyExt.invoke(MBeanProxyExt.java:210)
 $Proxy79.getDashboard(Unknown Source)
 org.jboss.portal.core.aspects.controller.PageCustomizerInterceptor.injectDashboardNav(PageCustomizerInterceptor.java:191)
 org.jboss.portal.core.aspects.controller.PageCustomizerInterceptor.invoke(PageCustomizerInterceptor.java:127)
 ***.***.portal.aspects.controller.PageCustomizerInterceptor.invoke(PageCustomizerInterceptor.java:37)
...

The last PageCustomizerInterceptor is a subclass of the one that comes with the portal. However, this used to work fine on portal 2.6.0.DR1. Since I switched the portal version, I can see the login page, but after hitting the login button, I'm presented with this exception.

I suspect it is related to the fact that our portal is heavily hacked into, in order to change the default theme, but I'm not sure...

Any ideas/hints/pointers/anything?