Thank you Peter! Follow your instruction, I add -verbose:class to JAVA_OPTS to run.bat, when jboss starts, I get a long class load list, In this list, I find these classes either loaded from jboss_home or java_home, and not know whick one is the stray JAR file. With no solution, I copy the whole jboss directory to other windows platform, On new windows platform, I call web service successfully! But On first windows platform, exception still occurs. My two windows platform have similar Enviroment Setting, and I still in doubt what's the root cause of the exception. View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4231535#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...