I'm getting this error when running xhtml page , 

```
java.lang.NoClassDefFoundError: org/java/plugin/ExtensionPoint
        at java.lang.Class.getDeclaredMethods0(Native Method)
        at java.lang.Class.privateGetDeclaredMethods(Unknown Source)
        at java.lang.Class.getDeclaredMethod(Unknown Source)
        at java.awt.Component.isCoalesceEventsOverriden(Unknown Source)
        at java.awt.Component.access$500(Unknown Source)
        at java.awt.Component$3.run(Unknown Source)
        at java.awt.Component$3.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.awt.Component.checkCoalescing(Unknown Source)
        at java.awt.Component.<init>(Unknown Source)
        at java.awt.Container.<init>(Unknown Source)
        at java.awt.Panel.<init>(Unknown Source)
        at java.awt.Panel.<init>(Unknown Source)
        at java.applet.Applet.<init>(Unknown Source)
        at javax.swing.JApplet.<init>(Unknown Source)
        at org.objectweb.salome_tmf.ihm.admin.AdministrationFinal.<init>(AdministrationFinal.java:73)
        at tn.talan.testFramework.managedBean.GestionUtilisateurMB.<init>(GestionUtilisateurMB.java:72)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
        at java.lang.reflect.Constructor.newInstance(Unknown Source)
        at java.lang.Class.newInstance0(Unknown Source)
        at java.lang.Class.newInstance(Unknown Source)
        at com.sun.faces.mgbean.BeanBuilder.newBeanInstance(BeanBuilder.java:184)
        at com.sun.faces.mgbean.BeanBuilder.build(BeanBuilder.java:98)
        at com.sun.faces.mgbean.BeanManager.createAndPush(BeanManager.java:405)
        at com.sun.faces.mgbean.BeanManager.create(BeanManager.java:265)
        at com.sun.faces.el.ManagedBeanELResolver.resolveBean(ManagedBeanELResolver.java:191)
        at com.sun.faces.el.ManagedBeanELResolver.getValue(ManagedBeanELResolver.java:73)
        at com.sun.faces.el.DemuxCompositeELResolver._getValue(DemuxCompositeELResolver.java:173)
        at com.sun.faces.el.DemuxCompositeELResolver.getValue(DemuxCompositeELResolver.java:200)
        at org.apache.el.parser.AstIdentifier.getValue(AstIdentifier.java:72)
        at org.apache.el.parser.AstValue.getValue(AstValue.java:147)
        at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:189)
        at com.sun.faces.facelets.el.ELText$ELTextVariable.toString(ELText.java:210)
        at com.sun.faces.facelets.compiler.AttributeInstruction.write(AttributeInstruction.java:86)
        at com.sun.faces.facelets.compiler.UIInstructions.encodeBegin(UIInstructions.java:78)
        at com.sun.faces.facelets.compiler.UILeaf.encodeAll(UILeaf.java:179)
        at javax.faces.render.Renderer.encodeChildren(Renderer.java:164)
        at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:849)
        at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1663)
        at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1666)
        at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1666)
        at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:389)
        at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:127)
        at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:117)
        at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:97)
        at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:135)
        at javax.faces.webapp.FacesServlet.service(FacesServlet.java:335)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
        at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
        at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1001)
        at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:579)
        at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
        at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.ClassNotFoundException: org.java.plugin.ExtensionPoint
        at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1711)
        at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1556)
        at java.lang.ClassLoader.loadClassInternal(Unknown Source)
        ... 65 more

```

i google for it bur didn't find any solution :(
i tried to run the project in another PC everything goes well (i'm using the same enviroment (eclipse,tomcat...) )

Thank you for advance