If we redeploy jbpm on JBoss 4.0.4 we get an exception from ehcache:
Caused by: org.hibernate.cache.CacheException: Attempt to restart an already started EhCacheProvider. Use sessionFactory.close() between repeated calls to buildSessionFactory. Consider using net.sf.ehcache.hibernate.SingletonEhCacheProvider. Error from ehcache was: Cannot parseConfiguration CacheManager. Attempt to create a new instance of CacheManager using the diskStorePath "null" which is already used by an existing CacheManager. The source of the configuration was classpath. at org.hibernate.cache.EhCacheProvider.start(EhCacheProvider.java:133)
I had similar problems, but based on another thread in the forum, I switched ehcache-1.1.jar to ehcache-1.2.jar and the problem went past the one you highlight.
I still have other issues...though. This time I get a "Table not found..." exception for one of the timer related query. You have to download hibernate 3.2.0.cr2 from sourceforge to get ehcache-1.2.jar.