[JSP] Eccezione generata da servlet

[PinoAntonino]

In una servlet ho la seguente eccezione

28-nov-2006 12.51.17 org.apache.catalina.core.StandardWrapperValve invoke
GRAVE: Servlet.service() for servlet LoginHandler threw exception
java.lang.IllegalStateException
        at org.apache.catalina.connector.ResponseFacade.sendRedirect(ResponseFacade.java:423)
        at javax.servlet.http.HttpServletResponseWrapper.sendRedirect(HttpServletResponseWrapper.java:125)
        at JavaVideoServer.LoginHandler.doPost(LoginHandler.java:49)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
        at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:362)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:482)
        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)

Fosse necessario un try catch lo risolverei.
Ma come mai, riavvio il server tomcat ricompilo la classe ma l'errore è sempre nella stessa riga nonostante inserisca anche 10 righe vuote dove si trova la riga incriminata?

[PinoAntonino]

Addirittura l'IDE Netbeans mi da l'eccezione anche quando tolgo la classe dal progetto.
Come mai?