This appears to be similar to http://java.net/jira/browse/GLASSFISH-12937
It appears to happen if/when a logged in administration console times out and then you try to use the UI, eg. click on the Home button after the timeout.
I've attached the stack trace that occurs in the server.log when this happens.
Once this happens the admin GUI is no longer accessible until you restart the server which is a real problem for production environments.