Thanks to the assistance of Ben Wang, this has been resolved; Thanks Ben! I was using the libs and lib50s from the PojoCache distribution to do my aopc compiling. It seems there was an incompatibility the jar files in that distribution, with the ones that are used to run the aop portions under the AS version 4.0.4.GA. I ended up taking jboss-aop-jdk50.jar from the deploy/jboss-aop-jdk50.deployer directory from jboss-4.0.5.GA, to use instead of the one that came w/ the cache distribution, and the javassist.jar from the default/lib folder from a version of JBoss 4.0.4.GA with the EJB3 installation... Overwriting those jar files and re-doing the aopc, all's well. Windows showed the correct javassist.jar to be of size 459,663 bytes, and the correct jboss-aop-jdk50.jar file to be of 909,125 bytes. I'm sure this will be cleared up soon, but perhaps this will help someone else who crosses this bridge, and to whom my issue appears familiar. Thanks, Jeff View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4003949#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...