EJBAdaptorBean not found

Hi,

On starting JBOSS 3.0 I get the following error:

12:44:56,046 INFO [MainDeployer] Starting deployment of package: file:/C:/jboss-3.0.4_tomcat-4.1.12/server/default/deploy/jmx-ejb-adaptor.jar
12:44:56,421 ERROR [EJBDeployer] Verfiy failed
java.lang.NoClassDefFoundError: org/jboss/jmx/adaptor/ejb/EJBAdaptorBean

although the jmx-ejb-adaptor.jar exists and this class is there.
Could you please advise what could cause this problem.

Thanks in advance.

Tanya