A heads up that there are several reports of problems using JAXB RI 2.2.3 with docx4j.
If you are encountering this, you should use an earlier implementation of JAXB (via the endorsed dir mechanism, if necessary).
JAXB RI 2.2.3 is used inter alia in Metro 2.1 [1] (and via that, Glassfish 3.1).
I've had a quick look at http://java.net/jira/browse/jaxb but couldn't see any relevant issues. I will investigate further in due course .. anyone else is of course welcome to contribute any findings to this thread.
[1] http://metro.java.net/2.1/