Before the beta release of jaxb 1.0, oracle application server for java (oc4j 9.0.2 and oc4j 9.0.3) has it own jaxb package under j2ee\home directory. The file is jaxb-rt-1.0-ea.jar. This jar file has some obsolute implementations of jaxb functions and comes earlier in the applications classpath. Many conflictions between local copy of jaxb 1.0 beta release (in web-inf/class or web-inf/lib of your deployments) and oracle jaxb runtime occur if the jaxb-rt-1.0-ea.jar presents. Try delete the file or change its file extension if any strange exception raises.