From the forum:

• http://forums.opensymphony.com/thread.jspa?threadID=47061&tstart=0

Robert Watkins: "Anyone who is trying to deploy multiple WebWork-based web applications in a single EAR file to Glassfish or Sun App Server 9 should probably check out this bug:

https://glassfish.dev.java.net/issues/show_bug.cgi?id=1351

Basically, with the default configuration, Enterprise apps would share the webwork JARs (particularly xwork) which means the static configuration gets "shared" to. Probably not what you want, and definitely not what I want.

It appears that disabling classloader delegation for the web app removes the shared state, allowing you to work around the problem at the cost of increased memory usage."