The latest JBoss release - JBoss-3.0.6_Tomcat-4.1.18 on IBM JDK 1.4 has problems with IBM Java2 SDK 1.4.0. It gives the following error during startup:
6:25:28,089 ERROR [MainDeployer] could not start deployment: file:/usr/local/jboss/server/default/conf/jboss-service.xml
at sun.reflect.GeneratedMethodAccessor5.invoke(Unknown Source)
There is no such problam with Sun j2sdk 1.4.1, though.
This is an old problem.
See: http://www.jboss.org/modules/bb/index.html?module=bb&op=viewtopic&t=forums/ have found no combination that results in getting 3.0.6 with Tomcat 4.1.18 to work with IBM JDK 1.4.0. Not compiling it with the IBM JDK or anything else seems to fix the issue.
Hopefully this will get resolved at some future point.