What is your exception exactly ? Do you use Spring's TransactionProxyFactoryBean ?
I don't think this is a problem within Hibernate. I also met some class loader problems when trying to integrate Spring/Hibernate inside Axis2(it was real pain to make everything work together!). I am convinced that Spring is the cause. See my post at
http://forum.springframework.org/showthread.php?t=39652. See also
http://ws.apache.org/axis2/1_1/spring.html. As you use Spring 2, you can set a classloader on the TransactionProxyFactoryBean... Hope this helps!