JBuilder 2005 新建Servlet报错

我在 JBuilder 2005 中 新建sevrlet 报错（未做任何修改）
环境变量配置没问题，因为这个问题装了几次系统了 刚刚装好系统后一两天没什么 问题
可是过几天后就出现这个问题 真的是奇怪 各位高手帮忙看看！报的如下错误：
严重: Error loading WebappClassLoader
  delegate: false
  repositories:
----------> Parent Classloader:
org.apache.catalina.loader.StandardClassLoader@1aaf0b3
 untitled1.Servlet1
java.lang.ClassNotFoundException: untitled1.Servlet1
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1332)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1181)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1027)
at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:750)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:130)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:856)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:744)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
at java.lang.Thread.run(Thread.java:595)
2007-10-10 10:43:58 org.apache.catalina.core.StandardWrapperValve invoke
严重: Allocate exception for servlet servlet1
java.lang.ClassNotFoundException: untitled1.Servlet1
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1332)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1181)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1027)
at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:750)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:130)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:856)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:744)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
at java.lang.Thread.run(Thread.java:595)