There are four possible bugs below, although they don't affect the use of my app. Any advice or causing by my mistaken configuration, please let me know. Your comments are appreciated. Many thanks.

1.

08:20:40,512 WARN [arjLoggerI18N] [com.arjuna.ats.arjuna.recovery.ActionStatusService_2] - Other Exception: java.lang.NullPointerException
08:20:40,555 ERROR [STDERR] java.lang.NullPointerException
08:20:40,555 ERROR [STDERR] at com.arjuna.ats.arjuna.recovery.ActionStatusService.doWork(ActionStatusService.java:123)
08:20:40,556 ERROR [STDERR] at com.arjuna.ats.internal.arjuna.recovery.Connection.run(Connection.java:83)

2009-05-29 13:41:22,910 ERROR [STDERR] (main) log4j:ERROR A "org.jboss.logging.appender.FileAppender" object is not assignable to a "org.apache.log4j.Appender" variable.
2009-05-29 13:41:22,934 ERROR [STDERR] (main) log4j:ERROR The class "org.apache.log4j.Appender" was loaded by
2009-05-29 13:41:22,935 ERROR [STDERR] (main) log4j:ERROR [BaseClassLoader@da7565{vfsfile:/work/jboss-5.0.1.GA/server/default/deploy/ROOT.war/}] whereas object of type
2009-05-29 13:41:22,935 ERROR [STDERR] (main) log4j:ERROR "org.jboss.logging.appender.FileAppender" was loaded by [org.jboss.system.NoAnnotationURLClassLoader@34a1fc].
2009-05-29 13:41:22,935 ERROR [STDERR] (main) log4j:ERROR Could not instantiate appender named "FILE".

13:40:37,861 DEBUG [AbstractManagedObjectFactory] Created skeleton ManagedObject: ManagedObject{org.jboss.beans.metadata.plugins.AbstractBeanMetaData}
13:40:37,861 DEBUG [BeanMetaDataICF] Using bean class:, class org.jboss.beans.metadata.plugins.AbstractBeanMetaData for bean: AbstractBeanMetaData@1a6eeab{name=BeansDeploymentAopMetaDataDeployer bean=org.jboss.aop.asintegration.jboss5.BeansDeploymentAopMetaDataDeployer properties=[kernel, aspectManager] classLoader=AbstractClassLoaderMetaData@1364dcb{classloader=AbstractDependencyValueMetaData@b91602{value=deployers-classloader:0.0.0}} constructor=null autowireCandidate=true}
13:40:37,863 DEBUG [BeanMetaDataICF] Failed to get property value for bean: org.jboss.beans.metadata.plugins.AbstractBeanMetaData, property: properties
java.lang.IllegalArgumentException: Property is not readable: propertyReplace for org.jboss.beans.metadata.plugins.AbstractPropertyMetaData
 at org.jboss.beans.info.plugins.DefaultPropertyInfo.get(DefaultPropertyInfo.java:131)
 at org.jboss.beans.info.plugins.BeanInfoUtil.getNestedTarget(BeanInfoUtil.java:78)
 at org.jboss.beans.info.plugins.BeanInfoUtil.get(BeanInfoUtil.java:142)
 at org.jboss.beans.info.plugins.AbstractBeanInfo.getProperty(AbstractBeanInfo.java:284)
 at org.jboss.metatype.plugins.values.DefaultMetaValueFactory.createCompositeValue(DefaultMetaValueFactory.java:471)
 at org.jboss.metatype.plugins.values.DefaultMetaValueFactory.internalCreate(DefaultMetaValueFactory.java:1023)
 at org.jboss.metatype.plugins.values.DefaultMetaValueFactory.createCollectionValue(DefaultMetaValueFactory.java:247)
 at org.jboss.metatype.plugins.values.DefaultMetaValueFactory.internalCreate(DefaultMetaValueFactory.java:1029)
 at org.jboss.metatype.plugins.values.DefaultMetaValueFactory.create(DefaultMetaValueFactory.java:542)
 at org.jboss.deployers.plugins.managed.BeanMetaDataICF.getValue(BeanMetaDataICF.java:165)
 at org.jboss.deployers.plugins.managed.BeanMetaDataICF.getValue(BeanMetaDataICF.java:48)
 at org.jboss.managed.plugins.factory.AbstractManagedObjectPopulator.populateValues(AbstractManagedObjectPopulator.java:201)
 at org.jboss.managed.plugins.factory.AbstractManagedObjectPopulator.populateManagedObject(AbstractManagedObjectPopulator.java:130)
 at org.jboss.managed.plugins.factory.AbstractManagedObjectFactory.initManagedObject(AbstractManagedObjectFactory.java:364)
 at org.jboss.managed.api.factory.ManagedObjectFactory.initManagedObject(ManagedObjectFactory.java:77)
 at org.jboss.system.server.profileservice.ProfileServiceBootstrap.initBootstrapMDs(ProfileServiceBootstrap.java:466)
 at org.jboss.system.server.profileservice.ProfileServiceBootstrap.start(ProfileServiceBootstrap.java:199)
 at org.jboss.bootstrap.AbstractServerImpl.start(AbstractServerImpl.java:405)
 at org.jboss.Main.boot(Main.java:209)
 at org.jboss.Main$1.run(Main.java:547)
 at java.lang.Thread.run(Thread.java:619)
13:40:37,863 DEBUG [ProfileServiceBootstrap] Created ManagedObject: ManagedObject{BeansDeploymentAopMetaDataDeployer} for bean: BeansDeploymentAopMetaDataDeployer
13:40:37,863 DEBUG [ProfileServiceBootstrap] Created ManagedComponent of type: ComponentType{type=MCBean, subtype=*} for bean: BeansDeploymentAopMetaDataDeployer

13:40:38,487 DEBUG [AbstractDeploymentContext] Added component VFSCache$realCache#1 to file:/work/jboss-5.0.1.GA/server/default/conf/bootstrap/vfs.xml
13:40:38,487 DEBUG [ProfileServiceBootstrap] Failed to build ManagedDeployment for: AbstractKernelDeployment@14aa6c3{name=file:/work/jboss-5.0.1.GA/server/default/conf/bootstrap/vfs.xml installed=true beanFactories=[AbstractBeanMetaData@50a492{name=VFSCache bean=null properties=[realCache, permanentRoots] constructor=AbstractConstructorMetaData@5a3923{parameters=[null] factoryClass=org.jboss.virtual.spi.cache.VFSCacheFactory factoryMethod=getInstance} autowireCandidate=true start=AbstractLifecycleMetaData@15d616e{ whenRequired=ControllerState@6481eb{Start} parameters= }}, AbstractBeanMetaData@8d8f67{name=VfsNamesExceptionHandler bean=org.jboss.virtual.plugins.context.helpers.NamesExceptionHandler properties= constructor=AbstractConstructorMetaData@1c1eceb{parameters=[java.lang.String]} autowireCandidate=true}]}
org.jboss.deployers.spi.DeploymentException: Error deploying: file:/work/jboss-5.0.1.GA/server/default/conf/bootstrap/vfs.xml
 at org.jboss.deployers.spi.DeploymentException.rethrowAsDeploymentException(DeploymentException.java:49)
 at org.jboss.deployers.vfs.deployer.kernel.BeanMetaDataFactoryVisitor.deploy(BeanMetaDataFactoryVisitor.java:136)
 at org.jboss.system.server.profileservice.ProfileServiceBootstrap.initBootstrapMDs(ProfileServiceBootstrap.java:453)
 at org.jboss.system.server.profileservice.ProfileServiceBootstrap.start(ProfileServiceBootstrap.java:199)
 at org.jboss.bootstrap.AbstractServerImpl.start(AbstractServerImpl.java:405)
 at org.jboss.Main.boot(Main.java:209)
 at org.jboss.Main$1.run(Main.java:547)
 at java.lang.Thread.run(Thread.java:619)
Caused by: java.lang.IllegalStateException: ClassLoader has not been set
 at org.jboss.deployers.structure.spi.helpers.AbstractDeploymentUnit.getClassLoader(AbstractDeploymentUnit.java:152)
 at org.jboss.deployers.vfs.deployer.kernel.BeanMetaDataFactoryVisitor.addBeanComponent(BeanMetaDataFactoryVisitor.java:60)
 at org.jboss.deployers.vfs.deployer.kernel.BeanMetaDataFactoryVisitor.deploy(BeanMetaDataFactoryVisitor.java:126)
 ... 6 more