Tomcat 6.0.29 JSP Error

bonjour,
Je rencontre un problème avec Tomcat 6.0.29. en fait j'essai d’exécuter les exemples de Tomcat en JSP mais ca donne des exceptions
Code:
Etat HTTP 500 -
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exception
 
javax.servlet.ServletException: Could not initialize class org.apache.jasper.compiler.JspRuntimeContext
	org.apache.catalina.security.SecurityUtil.execute(SecurityUtil.java:324)
	org.apache.catalina.security.SecurityUtil.doAsPrivilege(SecurityUtil.java:162)
	org.apache.catalina.security.SecurityUtil.doAsPrivilege(SecurityUtil.java:115)
	org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:470)
	org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
	org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
	org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
	org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
	org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
	java.lang.Thread.run(Unknown Source)
cause mère
 
java.lang.NoClassDefFoundError: Could not initialize class org.apache.jasper.compiler.JspRuntimeContext
	org.apache.jasper.servlet.JspServlet.init(JspServlet.java:102)
	sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	java.lang.reflect.Method.invoke(Unknown Source)
	org.apache.catalina.security.SecurityUtil$1.run(SecurityUtil.java:269)
	java.security.AccessController.doPrivileged(Native Method)
	javax.security.auth.Subject.doAsPrivileged(Unknown Source)
	org.apache.catalina.security.SecurityUtil.execute(SecurityUtil.java:301)
	org.apache.catalina.security.SecurityUtil.doAsPrivilege(SecurityUtil.java:162)
	org.apache.catalina.security.SecurityUtil.doAsPrivilege(SecurityUtil.java:115)
	org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:470)
	org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
	org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
	org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
	org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
	org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
	java.lang.Thread.run(Unknown Source)