ClassNotFoundException using shutdown.sh when JMxremote enabled.

Issue

When enabling the JMXremote features of the JVM on a JBoss 5.1.2 server configuration the following error is generated when calling the /bin/shutdown.sh

javax.management.JMRuntimeException: Failed to load MBeanServerBuilder class org.jboss.system.server.jmx.MBeanServerBuilderImpl: java.lang.ClassNotFoundException: org.jboss.system.server.jmx.MBeanServerBuilderImpl
        at javax.management.MBeanServerFactory.checkMBeanServerBuilder(MBeanServerFactory.java:480)
        at javax.management.MBeanServerFactory.getNewMBeanServerBuilder(MBeanServerFactory.java:511)
        at javax.management.MBeanServerFactory.newMBeanServer(MBeanServerFactory.java:298)
        at javax.management.MBeanServerFactory.createMBeanServer(MBeanServerFactory.java:213)
        at javax.management.MBeanServerFactory.createMBeanServer(MBeanServerFactory.java:174)
        at sun.management.ManagementFactory.createPlatformMBeanServer(ManagementFactory.java:302)
        at java.lang.management.ManagementFactory.getPlatformMBeanServer(ManagementFactory.java:504)
        at sun.management.jmxremote.ConnectorBootstrap.initialize(ConnectorBootstrap.java:392)
        at sun.management.Agent.startAgent(Agent.java:127)
        at sun.management.Agent.startAgent(Agent.java:239)
Caused by: java.lang.ClassNotFoundException: org.jboss.system.server.jmx.MBeanServerBuilderImpl
        at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
        at javax.management.MBeanServerFactory.loadBuilderClass(MBeanServerFactory.java:423)
        at javax.management.MBeanServerFactory.checkMBeanServerBuilder(MBeanServerFactory.java:465)
        ... 9 more
Exception thrown by the agent : javax.management.JMRuntimeException: Failed to load MBeanServerBuilder class org.jboss.system.server.jmx.MBeanServerBuilderImpl: java.lang.ClassNotFoundException: org.jboss.system.server.jmx.MBeanServerBuilderImpl

The following JMX related options are being pasted to the server instance on startup and no issues are being seen at startup, just when calling the shutdown.

    JAVA_OPTS="$JAVA_OPTS -Djboss.platform.mbeanserver"
    JAVA_OPTS="$JAVA_OPTS -Dcom.sun.management.jmxremote"
    JAVA_OPTS="$JAVA_OPTS -Dcom.sun.management.jmxremote.ssl=false"
    JAVA_OPTS="$JAVA_OPTS -Dcom.sun.management.jmxremote.authenticate=false"
    JAVA_OPTS="$JAVA_OPTS -Dcom.sun.management.jmxremote.port=9007"
    JAVA_OPTS="$JAVA_OPTS -Djavax.management.builder.initial=org.jboss.system.server.jmx.MBeanServerBuilderImpl"