I notice that your are using JDK 6u10 - I have run into various strange problems when using that version. Could you try using 6u7 (if you have it) or get 6u12 (the latest) and try it. You installed JBoss AS into a directory with spaces in its path ("jboss server"). Don't do that - spaces in the path can confuse various Java libraries. Please rename the directory to something like jboss_server. If you still have issues, add "-verbose:class" to the JAVA_OPTS in run.bat. It is possible that you have a stray jaxb(?) JAR file being picked up somewhere. The -verbose:class option will print out the JAR file location for every class loaded - look for the two classes mentioned in the "caused by" clause: Caused by: java.lang.ClassCastException: org.apache.xerces.parsers.StandardParserConfiguration cannot be cast to org.apache.xerces.xni.parser.XMLParserConfiguration View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4219545#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...