The entire message from the log file is:

===============================================================================

JBoss Bootstrap Environment

JBOSS_HOME: C:\jboss-4.0.5.GA\jboss-4.0.5.GA\bin\\..

JAVA: C:\Program Files\Java\j2sdk1.5.0\bin\java

JAVA_OPTS: -Dprogram.name=run.bat -server -Xms128m -Xmx512m -Dsun.rmi.dgc.client.gcInterval=3600000 -Dsun.rmi.dgc.server.gcInterval=3600000

CLASSPATH: C:\Program Files\Java\j2sdk1.5.0\lib\tools.jar;C:\jboss-4.0.5.GA\jboss-4.0.5.GA\bin\\run.jar

===============================================================================

12:59:14,593 INFO [Server] Starting JBoss (MX MicroKernel)...
12:59:14,593 INFO [Server] Release ID: JBoss [Zion] 4.0.5.GA (build: CVSTag=Branch_4_0 date=200610162339)
12:59:14,593 INFO [Server] Home Dir: C:\jboss-4.0.5.GA\jboss-4.0.5.GA
12:59:14,593 INFO [Server] Home URL: file:/C:/jboss-4.0.5.GA/jboss-4.0.5.GA/
12:59:14,593 INFO [Server] Patch URL: null
12:59:14,593 INFO [Server] Server Name: default
12:59:14,593 INFO [Server] Server Home Dir: C:\jboss-4.0.5.GA\jboss-4.0.5.GA\server\default
12:59:14,593 INFO [Server] Server Home URL: file:/C:/jboss-4.0.5.GA/jboss-4.0.5.GA/server/default/
12:59:14,593 INFO [Server] Server Log Dir: C:\jboss-4.0.5.GA\jboss-4.0.5.GA\server\default\log
12:59:14,593 INFO [Server] Server Temp Dir: C:\jboss-4.0.5.GA\jboss-4.0.5.GA\server\default\tmp
12:59:14,593 INFO [Server] Root Deployment Filename: jboss-service.xml
12:59:14,765 WARN [BasicMBeanRegistry] javax.management.MBeanRegistrationException: preRegister() failed: [ObjectName='JMImplementation:type=MBeanServerDelegate', Class=javax.management.MBeanServerDelegate (javax.management.MBeanServerDelegate@e0b6f5)]
Failed to boot JBoss
java.lang.RuntimeException: Cannot create MBeanServer
at org.jboss.mx.server.MBeanServerImpl.(MBeanServerImpl.java:239)
at org.jboss.mx.server.MBeanServerBuilderImpl.newMBeanServer(MBeanServerBuilderImpl.java:71)
at javax.management.MBeanServerFactory.newMBeanServer(MBeanServerFactory.java:316)
at javax.management.MBeanServerFactory.createMBeanServer(MBeanServerFactory.java:219)
at org.jboss.system.server.ServerImpl.doStart(ServerImpl.java:420)
at org.jboss.system.server.ServerImpl.start(ServerImpl.java:362)
at org.jboss.Main.boot(Main.java:200)
at org.jboss.Main$1.run(Main.java:490)
at java.lang.Thread.run(Thread.java:566)
Caused by: javax.management.MBeanRegistrationException: preRegister() failed: [ObjectName='JMImplementation:type=MBeanServerDelegate', Class=javax.management.MBeanServerDelegate (javax.management.MBeanServerDelegate@e0b6f5)]
at org.jboss.mx.server.registry.BasicMBeanRegistry.invokePreRegister(BasicMBeanRegistry.java:713)
at org.jboss.mx.server.registry.BasicMBeanRegistry.registerMBean(BasicMBeanRegistry.java:211)
at org.jboss.mx.server.MBeanServerImpl.(MBeanServerImpl.java:215)
... 8 more
Caused by: javax.management.RuntimeOperationsException: Exception occured trying find the descriptors of the MBean
at javax.management.modelmbean.ModelMBeanInfoSupport.getDescriptors(ModelMBeanInfoSupport.java:445)
at org.jboss.mx.modelmbean.ModelMBeanInvoker.initPersistence(ModelMBeanInvoker.java:538)
at org.jboss.mx.modelmbean.ModelMBeanInvoker.init(ModelMBeanInvoker.java:520)
at org.jboss.mx.modelmbean.ModelMBeanInvoker.invokePreRegister(ModelMBeanInvoker.java:486)
at org.jboss.mx.server.AbstractMBeanInvoker.preRegister(AbstractMBeanInvoker.java:654)
at org.jboss.mx.server.registry.BasicMBeanRegistry.invokePreRegister(BasicMBeanRegistry.java:697)
... 10 more
Caused by: java.lang.IllegalArgumentException: Descriptor Type is invalid
... 16 more

I finally got JBoss to boot!

Information I got was that, jboss-4.0.5.GA often has problems with earlier version of jdk1.5.

I just had to install a later version of the jdk and the server booted just fine.

Thanks all