Perhaps at runtime you are picking up a stray version of the POI JAR file. Try this: add the "-verbose:class" JVM option to JAVA_OPTS in run.bat (Windows) or run.conf (Linux). Redirect stdout and stderr to a file (you will get a lot of output). When you runn, each time a class is loaded the JVM will tell you which JAR file contains the class. This should help you locate the offending JAR file. View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4226634#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...