this error is because you have the web classes in your jar as well. (should only have them in war).
What you might want to do is have it the other way around which is for example an ejb-client.jar which just has your home interface of your session bean so your web side can make a reference and call your bean.
You will need this in the classpath of your war manifest. Then your struts action, for example can look it up and you will have your link to your model.
Thanks for the quick reply!
I will try this and let you know. It sounds logical to me anyway.