Structs2中总是提示Exception starting filter struts2错误

各位高手，我现在在学Structs2，用一个现成的Structs2项目在myeclipse中用tomcat6.0运行后总是提示下面的错误，查了好久还是没找到原因：
严重: Exception starting filter struts2
java.lang.NullPointerException
at com.opensymphony.xwork2.util.FileManager$FileRevision.needsReloading(FileManager.java:209)
at com.opensymphony.xwork2.util.FileManager.fileNeedsReloading(FileManager.java:60)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.needsReload(XmlConfigurationProvider.java:325)
at org.apache.struts2.config.StrutsXmlConfigurationProvider.needsReload(StrutsXmlConfigurationProvider.java:168)
at com.opensymphony.xwork2.config.ConfigurationManager.conditionalReload(ConfigurationManager.java:220)
at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:61)
at org.apache.struts2.dispatcher.Dispatcher.getContainer(Dispatcher.java:774)
at org.apache.struts2.dispatcher.ng.InitOperations.initStaticContentLoader(InitOperations.java:77)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.init(StrutsPrepareAndExecuteFilter.java:49)
at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:295)
at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:422)
at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:115)
at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4072)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4726)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:799)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:779)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:601)
at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1079)
at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:1002)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:506)
at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1317)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:324)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:142)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1065)
at org.apache.catalina.core.StandardHost.start(StandardHost.java:840)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1057)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:463)
at org.apache.catalina.core.StandardService.start(StandardService.java:525)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:754)
at org.apache.catalina.startup.Catalina.start(Catalina.java:595)
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:597)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)
2012-4-25 16:00:18 org.apache.catalina.core.StandardContext start
严重: Error filterStart
2012-4-25 16:00:18 org.apache.catalina.core.StandardContext start
严重: Context [/Struts2_0200_Namespace] startup failed due to previous errors
2012-4-25 16:00:18 org.apache.catalina.loader.WebappClassLoader clearThreadLocalMap
严重: The web application [/Struts2_0200_Namespace] created a ThreadLocal with key of type [com.opensymphony.xwork2.inject.ContainerImpl$10] (value [com.opensymphony.xwork2.inject.ContainerImpl$10@16b321b]) and a value of type [java.lang.Object[]] (value [[Ljava.lang.Object;@a6cbf7]) but failed to remove it when the web application was stopped. This is very likely to create a memory leak.
2012-4-25 16:00:18 org.apache.catalina.loader.WebappClassLoader clearThreadLocalMap
严重: The web application [/Struts2_0200_Namespace] created a ThreadLocal with key of type [com.opensymphony.xwork2.inject.ContainerImpl$10] (value [com.opensymphony.xwork2.inject.ContainerImpl$10@98f192]) and a value of type [java.lang.Object[]] (value [[Ljava.lang.Object;@11bd9c9]) but failed to remove it when the web application was stopped. This is very likely to create a memory leak.用到的Structs2包有下边几个：
commons-fileupload-1.2.1.jar
commons-io-1.3.2.jar
commons-logging-1.1.jar
freeer-2.3.13.jar
ognl-2.6.11.jar
struts2-core-2.1.6.jar
xwork-2.1.2.jar到底是什么原因呢？我看视频做的，里边没问题啊，到了我的电脑就有问题了！