Hi,
does your application contain the Xerces XML parser libraries?
This error message points at this problem:
Caused by: java.lang.ClassCastException: org.apache.xerces.parsers.XML11Configuration cannot be cast to org.apache.xerces.xni.parser.XMLParserConfiguration
As JBoss already bundles Xerces, easiest fix is to remove all XML parser related JARs from your app. If this is not possible, you have to play around with classloader configuration.
Best regards
Wolfgang