求助各位大虾，在线等！
小弟在正在学Hibernate +Struts，今天下午写了一个小WEB程序，一点击用户注册的时候就弹出了以下错误，请各位高手指点~！小弟谢谢拉~！

%%%% Error Creating SessionFactory %%%%
java.lang.SecurityException: class "org.apache.commons.collections.SequencedHashMap"'s signer information does not match signer information of other classes in the same package
at java.lang.ClassLoader.checkCerts(Unknown Source)
at java.lang.ClassLoader.preDefineClass(Unknown Source)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:1819)
at org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:872)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1327)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1206)
at java.lang.ClassLoader.loadClassInternal(Unknown Source)
at org.hibernate.mapping.Table.<init>(Table.java:33)
at org.hibernate.cfg.Mappings.addTable(Mappings.java:165)
at org.hibernate.cfg.HbmBinder.bindRootPersistentClassCommonValues(HbmBinder.java:299)
at org.hibernate.cfg.HbmBinder.bindRootClass(HbmBinder.java:282)
at org.hibernate.cfg.HbmBinder.bindRoot(HbmBinder.java:153)
at org.hibernate.cfg.Configuration.add(Configuration.java:386)
at org.hibernate.cfg.Configuration.addInputStream(Configuration.java:427)
at org.hibernate.cfg.Configuration.addResource(Configuration.java:482)
at org.hibernate.cfg.Configuration.parseMappingElement(Configuration.java:1465)
at org.hibernate.cfg.Configuration.parseSessionFactory(Configuration.java:1433)
at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:1414)
at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:1390)
at org.hibernate.cfg.Configuration.configure(Configuration.java:1310)
at y2ssh.epai.xmal3.daoImpl.HibernateSessionFactory.<clinit>(HibernateSessionFactory.java:30)
at y2ssh.epai.xmal3.daoImpl.HibernateDAOImpl.add(HibernateDAOImpl.java:15)
at y2ssh.epai.xmal3.daoImpl.UserDAOImpl.adduser(UserDAOImpl.java:17)
at y2ssh.epai.xmal3.BziImpl.UserBizImpl.UserRegister(UserBizImpl.java:23)
at y2ssh.epai.xmal3.action.RegisterAction.execute(RegisterAction.java:48)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Unknown Source)
2008-04-30 14:27:58,609 INFO [org.hibernate.cfg.Configuration] configuring from resource: /hibernate.cfg.xml
2008-04-30 14:27:58,609 INFO [org.hibernate.cfg.Configuration] Configuration resource: /hibernate.cfg.xml