Read the release note on the class loading change in the web container. Presumably the resource is not being loaded from a war class and so it can no longer be found.
Thank you for your answer. I agree that the problem is in Tomcat. I realized that JBoss 4.0.2 has Tomcat 5.5 embedded while JBoss 4.0.1sp1 had Tomcat 5.0.
Tomcat claims that JDK 1.5 should be used with 5.5. I switched the JDK to 1.5 and still get the same problem with getBundle. I understand that this topic should be transferred to Tomcat group but if someone may help me here I would appreciate your help.
Also I tried to package version.property file into some application package so it would not be in the root of the classes directory and it did not help as well.