Why no one answers????!!!!!
I'm using JBPM 3.2.6 with Jboss AS 4.2.2. Is is a stable combination?
The problem might be that no one has faced this error before... at least you posted too little detail and context.
Have you looked up http://localhost:8080/jmx-console/HtmlAdaptor?action=inspectMBean&name=jboss%3Aservice%3DJNDIView (check host/port) which names and types are registered and checked jbpm and spring configuration files for correct usage of this names? Have you debugged the code?
What does your jbpm configuration look like?