You probably use a different version of xercesImpl.jar on the client, with that on the server.
I am getting the
at $Proxy1.getMBeanInfo(Unknown Source)
from the MEJB in JBoss 4.0.4 GA when the MBean throws an IOException. According to the code the XMBean throws an MBeanException in this case but somewhere along the line it is converted to an UndeclaredThrowableException.
This causes a problem because UndeclaredThrowableException is a runtime exception.
Mark P Ashworth