dont believe I have any background processes (cron jobs) running besides the app server and the database server.
the Jboss server is installed as a Windows Service using a wrapper from Tanukisoftware.com
WOuld this have anything to do with the problem?
The calls can fail due to the fact that the invocation layer is decoupled from the ejb container. You would have to customize the invoker mbean to listen for undeployment/deployment events and queue requests targeted at the ejb container when it was not deployed.