This week's giveaway is in the EJB and other Java EE Technologies forum. We're giving away four copies of EJB 3 in Action and have Debu Panda, Reza Rahman, Ryan Cuprak, and Michael Remijan on-line! See this thread for details.
Which version of S2? Where is your Tomcat deployed?
(At one point I recall an issue about deploying to directories w/ spaces in the name--try a non-spaced Tomcat deploy directory as a sanity-check.) Other than that I can't think of anything off the top of my head; I'm running under that environment just fine on three different OSs.