Still having the same problem. Here are some tests I've made, all give the same result:

- Ran the web app on JBoss 6 and Tomcat

- Played with different versions of included libs

- Played with templates and different options to define xhtmls (with headers, ui tags, etc.)

- Tried different JRE and JDK versions

The behaviour is still the same: Most of components work except for some like datatable navigation or form validation.

I'm sure I'm doing something terribly wrong. I remember I tried to play with RF4 some time before (it was v4.0.0 FInal) and I had absolutely no problems with those components.

Just for the reference here're my web.xml, faces-config and test xhtml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
          xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
          version="3.0">

          <display-name>Cambry v2.0</display-name>
          <description>Cambry v2.0</description>

          <welcome-file-list>
               <welcome-file>app</welcome-file>
          </welcome-file-list>

          <servlet>
               <servlet-name>StartupServlet</servlet-name>
               <servlet-class>org.cambry2.test.StartupServlet</servlet-class>
          </servlet>

          <servlet-mapping>
               <servlet-name>StartupServlet</servlet-name>
               <url-pattern>/app</url-pattern>
          </servlet-mapping>

          <servlet>
               <servlet-name>Faces Servlet</servlet-name>
               <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
               <load-on-startup>1</load-on-startup>
          </servlet>
          <servlet-mapping>
               <servlet-name>Faces Servlet</servlet-name>
               <url-pattern>*.faces</url-pattern>
          </servlet-mapping>
          <context-param>
               <param-name>org.richfaces.skin</param-name>
               <param-value>classic</param-value>
          </context-param>
</web-app>

<?xml version="1.0" encoding="UTF-8"?>
<faces-config
         xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-facesconfig_2_1.xsd"
         version="2.1">

        <converter>
               <converter-id>converterSI</converter-id>
               <converter-class>org.cambry2.converter.SIConverter</converter-class>
          </converter>

          <validator>
                   <validator-id>validatorSI</validator-id>
                   <validator-class>org.cambry2.validator.SIValidator</validator-class>
          </validator>

</faces-config>

<ui:composition xmlns="http://www.w3.org/1999/xhtml"
          xmlns:h="http://java.sun.com/jsf/html"
          xmlns:f="http://java.sun.com/jsf/core"
          xmlns:ui="http://java.sun.com/jsf/facelets"
          xmlns:a4j="http://richfaces.org/a4j"
          xmlns:rich="http://richfaces.org/rich">
<f:view>
<h:head/>
<h:body>
        <h:form>
               <a4j:jsFunction name="initialLoad" action="#{managedBean1.initialLoad}" render="form_carros"/>
          </h:form>

        <rich:panel>
                  <f:facet name="header">
                       <h:outputText value="Carritos admin"/>
                  </f:facet>

                  <h:form id="form_carros">
                        <rich:dataTable id="dt_carros" value="#{managedBean1.carros}" var="carro" rowKeyVar="row" rows="5">
                             <rich:column>
                                  <f:facet name="header">Marca</f:facet>
                                  <h:outputText value="#{carro.marca}"/>
                             </rich:column>
                             <rich:column style="text-align: right;">
                                   <f:facet name="header">Modelo</f:facet>
                                   <h:outputText value="#{carro.modelo}"/>
                              </rich:column>
                              <rich:column style="text-align: right;">
                                   <f:facet name="header">Precio</f:facet>
                                   <h:outputText value="#{carro.precio}">
                                             <f:convertNumber pattern="$#,###.00" type="currency" locale="es_MX"/>
                                   </h:outputText>
                              </rich:column>
                              <rich:column style="text-align: center;">
                                   <f:facet name="header">Vendido</f:facet>
                                   <h:outputText value="#{carro.vendido?'Sí':'No'}"/>
                              </rich:column>
                              <f:facet name="footer">
                                          <rich:dataScroller />
                                  </f:facet>
                        </rich:dataTable>

                        <rich:messages showSummary="true" showDetail="false" ajaxRendered="true" style="color: red;"/>
              </h:form>
        </rich:panel>

          <script type="text/javascript">
          window.onload = initialLoad;
          </script>

</h:body>
</f:view>
</ui:composition>

Edit:

Interesting observation: When I click any of datascroller's links a rich:messages shows an error: The button/link/text component needs to have a Form in its ancestry. Please add <h:form>.

Finally I made it work. Still I would very like to hear why that was happening...

The problem seems was with 2 forms I had. If I put both my a4j:jsFunction and rich:panel inside 1 form all works fine. As soon as I separate them datascroller stops working.

I'm really too tired to investigate the real cause (probably rendering/js_dom_tree processing nature) so if anyone has spare time it would be nice to understand the issue.