We seem to be affected by java.lang.NoSuchMethodError problem described more in Hibernate forum and Hibernate Jira.
The solution that works for us is switching to the server VM using -server switch while starting Tomcat. It works for our production VM, which is:java version "1.5.0_06"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_06-b05)
Java HotSpot(TM) Server VM (build 1.5.0_06-b05, mixed mode)