Hibernate version: 2

Mapping documents: nothing

Code between sessionFactory.openSession() and session.close():

Full stack trace of any exception that occurs:net.sf.hibernate.WrongClassException: Object with id: 1 was not of the specified subclass:
WsUserGroup (loaded object was of wrong class)
at net.sf.hibernate.loader.Loader.instanceAlreadyLoaded(Loader.java:300)
at net.sf.hibernate.loader.Loader.getRow(Loader.java:278)
at net.sf.hibernate.loader.Loader.doFind(Loader.java:159)
at net.sf.hibernate.loader.Loader.loadCollection(Loader.java:602)
at net.sf.hibernate.loader.OneToManyLoader.initialize(OneToManyLoader.java:102)
at net.sf.hibernate.impl.SessionImpl.initialize(SessionImpl.java:2897)
at net.sf.hibernate.collection.PersistentCollection.getInitialValue(PersistentCollection.java:128)
at net.sf.hibernate.type.PersistentCollectionType.getCollection(PersistentCollectionType.java:74)
at net.sf.hibernate.type.PersistentCollectionType.resolveIdentifier(PersistentCollectionType.java:177)
at net.sf.hibernate.impl.SessionImpl.initializeEntity(SessionImpl.java:1959)
at net.sf.hibernate.loader.Loader.doFind(Loader.java:196)
at net.sf.hibernate.loader.Loader.loadCollection(Loader.java:602)
at net.sf.hibernate.loader.OneToManyLoader.initialize(OneToManyLoader.java:102)
at net.sf.hibernate.impl.SessionImpl.initialize(SessionImpl.java:2897)
at net.sf.hibernate.collection.PersistentCollection.getInitialValue(PersistentCollection.java:128)
at net.sf.hibernate.type.PersistentCollectionType.getCollection(PersistentCollectionType.java:74)
at net.sf.hibernate.type.PersistentCollectionType.resolveIdentifier(PersistentCollectionType.java:177)
at net.sf.hibernate.impl.SessionImpl.initializeEntity(SessionImpl.java:1959)
at net.sf.hibernate.loader.Loader.doFind(Loader.java:196)
at net.sf.hibernate.loader.Loader.loadEntity(Loader.java:587)
at net.sf.hibernate.loader.EntityLoader.load(EntityLoader.java:42)
at net.sf.hibernate.persister.EntityPersister.load(EntityPersister.java:396)
at net.sf.hibernate.impl.SessionImpl.doLoad(SessionImpl.java:1889)
at net.sf.hibernate.impl.SessionImpl.doLoadByClass(SessionImpl.java:1757)
at net.sf.hibernate.impl.SessionImpl.load(SessionImpl.java:1688)

Name and version of the database you are using: MySQL 4.1

The generated SQL (show_sql=true):

Debug level Hibernate log excerpt:

One of the conditions under which this happens is when I have 2 different hbm files for same table. I read the record & when it's in memory, I try to get same record using the other class which has different set of properties (hbm file) & I noticed the error. If I close the session and reopen between these 2 reads, then it works fine.