root cause

java.lang.LinkageError: loader (instance of  org/apache/catalina/loader/WebappClassLoader): attempted  duplicate class definition for name: "com/assoft/comment/db/pojo/CommentFilter_$$_javassist_6"
    java.lang.ClassLoader.defineClass1(Native Method)
    java.lang.ClassLoader.defineClass(Unknown Source)
    sun.reflect.GeneratedMethodAccessor27.invoke(Unknown Source)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    java.lang.reflect.Method.invoke(Unknown Source)
    javassist.util.proxy.FactoryHelper.toClass2(FactoryHelper.java:177)
    javassist.util.proxy.FactoryHelper.toClass(FactoryHelper.java:159)
    org.jboss.seam.util.ProxyFactory.createClass(ProxyFactory.java:186)
    org.jboss.seam.Component.createProxyFactory(Component.java:2339)
    org.jboss.seam.Component.getProxyFactory(Component.java:1433)
    org.jboss.seam.Component.wrap(Component.java:1424)
    org.jboss.seam.Component.instantiateJavaBean(Component.java:1362)
    org.jboss.seam.Component.instantiate(Component.java:1279)
    org.jboss.seam.Component.newInstance(Component.java:2027)
    org.jboss.seam.Component.getInstance(Component.java:1931)
    org.jboss.seam.Component.getInstance(Component.java:1898)
    org.jboss.seam.Namespace.getComponentInstance(Namespace.java:55)
    org.jboss.seam.Namespace.getComponentInstance(Namespace.java:50)
    org.jboss.seam.el.SeamELResolver.resolveBase(SeamELResolver.java:166)
    org.jboss.seam.el.SeamELResolver.getValue(SeamELResolver.java:53)
    javax.el.CompositeELResolver.getValue(CompositeELResolver.java:53)
    com.sun.faces.el.FacesCompositeELResolver.getValue(FacesCompositeELResolver.java:72)
    org.jboss.el.parser.AstIdentifier.getValue(AstIdentifier.java:44)
    org.jboss.el.parser.AstValue.getValue(AstValue.java:63)
    org.jboss.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:186)
    com.sun.facelets.el.TagValueExpression.getValue(TagValueExpression.java:71)
    javax.faces.component.UIOutput.getValue(UIOutput.java:184)
    com.sun.faces.renderkit.html_basic.HtmlBasicInputRenderer.getValue(HtmlBasicInputRenderer.java:201)
    com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.getCurrentValue(HtmlBasicRenderer.java:284)
    com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeEnd(HtmlBasicRenderer.java:154)
    javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:861)
    javax.faces.component.UIComponent.encodeAll(UIComponent.java:946)
    javax.faces.render.Renderer.encodeChildren(Renderer.java:148)
    javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:837)
    javax.faces.component.UIComponent.encodeAll(UIComponent.java:936)
    javax.faces.component.UIComponent.encodeAll(UIComponent.java:942)
    com.sun.facelets.FaceletViewHandler.renderView(FaceletViewHandler.java:592)
    org.ajax4jsf.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:108)
    org.ajax4jsf.application.AjaxViewHandler.renderView(AjaxViewHandler.java:196)
    com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:109)
    com.sun.faces.lifecycle.Phase.doPhase(Phase.java:100)
    com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
    javax.faces.webapp.FacesServlet.service(FacesServlet.java:266)
    org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:522)
    org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:83)
    org.jboss.seam.web.IdentityFilter.doFilter(IdentityFilter.java:38)
    org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
    org.jboss.seam.web.MultipartFilter.doFilter(MultipartFilter.java:90)
    org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
    org.jboss.seam.web.ExceptionFilter.doFilter(ExceptionFilter.java:64)
    org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
    org.jboss.seam.web.RedirectFilter.doFilter(RedirectFilter.java:45)
    org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
    org.ajax4jsf.webapp.BaseXMLFilter.doXmlFilter(BaseXMLFilter.java:177)
    org.ajax4jsf.webapp.BaseFilter.handleRequest(BaseFilter.java:267)
    org.ajax4jsf.webapp.BaseFilter.processUploadsAndHandleRequest(BaseFilter.java:380)
    org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:507)
    org.jboss.seam.web.Ajax4jsfFilter.doFilter(Ajax4jsfFilter.java:56)
    org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
    org.jboss.seam.web.LoggingFilter.doFilter(LoggingFilter.java:58)
    org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
    org.jboss.seam.servlet.SeamFilter.doFilter(SeamFilter.java:158)
    com.assoft.comment.filter.SetEncodeFilter.doFilter(SetEncodeFilter.java:37)

note The full stack trace of the root cause is available in the Apache Tomcat/6.0.18 logs.
Apache Tomcat/6.0.18