很奇怪的问题,我得OS是XP,JDK是1.5,注册RMI服务总是有问题

我用了两种方法注册,一种可以,一种不行,我都快疯了!而且我还不很清楚这两者有什么区别
1使用UnicastRemoteObject.exportObject(mock,port);这种方法好像可以,但是我想用servlet启动它就不行了.
2使用一般RMI例子的Naming.rebind()总是报下面的错java.rmi.ServerException: RemoteException occurred in server thread; nested exce
ption is:
        java.rmi.UnmarshalException: error unmarshalling arguments; nested excep
tion is:
        java.lang.ClassNotFoundException: com.gxlu.miring.server.UserSynchronize
Impl_Stub
        at sun.rmi.server.UnicastServerRef.oldDispatch(UnicastServerRef.java:385
)
        at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:240)
        at sun.rmi.transport.Transport$1.run(Transport.java:153)
        at java.security.AccessController.doPrivileged(Native Method)
        at sun.rmi.transport.Transport.serviceCall(Transport.java:149)
        at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:4
60)
        at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport
.java:701)
        at java.lang.Thread.run(Thread.java:595)
        at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(Stream
RemoteCall.java:247)
        at sun.rmi.transport.StreamRemoteCall.executeCall(StreamRemoteCall.java:
223)
        at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:343)
        at sun.rmi.registry.RegistryImpl_Stub.bind(Unknown Source)
        at java.rmi.Naming.bind(Naming.java:111)
        at com.gxlu.miring.server.RMISwitch.startRMI(RMISwitch.java:51)
        at Test.RMITest.main(RMITest.java:35)使用1注册时候也报错,说已经bindingjava.rmi.server.ExportException: object already exported
at sun.rmi.transport.ObjectTable.putTarget(ObjectTable.java:172)
at sun.rmi.transport.Transport.exportObject(Transport.java:75)
at sun.rmi.transport.tcp.TCPTransport.exportObject(TCPTransport.java:190)
at sun.rmi.transport.tcp.TCPEndpoint.exportObject(TCPEndpoint.java:382)
at sun.rmi.transport.LiveRef.exportObject(LiveRef.java:116)
at sun.rmi.server.UnicastServerRef.exportObject(UnicastServerRef.java:180)
at java.rmi.server.UnicastRemoteObject.exportObject(UnicastRemoteObject.java:293)
at java.rmi.server.UnicastRemoteObject.exportObject(UnicastRemoteObject.java:235)
at com.gxlu.miring.server.RMIControl.startRMI(RMIControl.java:52)
at com.gxlu.miring.server.RMIServer.init(RMIServer.java:43)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1091)
at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:925)
at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:3857)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4118)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:759)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:739)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:524)
at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:788)
at org.apache.catalina.startup.HostConfig.deployWARs(HostConfig.java:677)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:473)
at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1102)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:311)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1020)
at org.apache.catalina.core.StandardHost.start(StandardHost.java:718)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1012)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:442)
at org.apache.catalina.core.StandardService.start(StandardService.java:450)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:683)
at org.apache.catalina.startup.Catalina.start(Catalina.java:537)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:271)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:409)但是如果是直接启动,客户端没问题,用servlet启动,一调用就出下面的错java.rmi.NotBoundException: UserSynchronize
at sun.rmi.registry.RegistryImpl.lookup(RegistryImpl.java:106)
at sun.rmi.registry.RegistryImpl_Skel.dispatch(Unknown Source)
at sun.rmi.server.UnicastServerRef.oldDispatch(UnicastServerRef.java:375)
at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:240)
at sun.rmi.transport.Transport$1.run(Transport.java:153)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Transport.java:149)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:460) at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:701)
at java.lang.Thread.run(Thread.java:595)
at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(StreamRemoteCall.java:247)
at sun.rmi.transport.StreamRemoteCall.executeCall(StreamRemoteCall.java:223)
at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:343)
at sun.rmi.registry.RegistryImpl_Stub.lookup(Unknown Source)
at java.rmi.Naming.lookup(Naming.java:84)
at Test.RMIClient.main(RMIClient.java:52)哪位大侠帮帮忙???解答一下我得问题