Hello, here is my code:

<ui:define name="leftZone">
  <h:form>
   <rich:panel header="Навигация">
    <rich:tree id="navigationTree" var="node"
     value="#{treeManager.rootNodes}" toggleType="ajax"
     selectionType="ajax"
     selectionChangeListener="#{treeManager.selectionChanged}"
     nodeType="#{node.type}" reRender="mainPanel" render="mainPanel">
     <rich:treeNode type="folder">
      #{node.name}
     </rich:treeNode>
    </rich:tree>
   </rich:panel>
  </h:form>
 </ui:define>

public void initTree() throws AsgeMetaException, AsgeEssenceOperationException {
    if (rootFolderId != null) {
      currentSelection = null;
      rootNodes.clear();
      // Получаем саму папку.
      AsgeEssenceId folderId = new AsgeEssenceId(rootFolderId);
      AsgeEssenceOperationManager eom = new AsgeEssenceOperationManager(folderId);
      eom.setGetLinkedObjects(false);
      AsgeFolder folder = (AsgeFolder) eom.getOne();
      // Добавляем саму папку в дерево (TODO: временно на стадии отладки)
      AsgeTreeNode node = new AsgeTreeNode(folder, null);
      node.setName(folder.getTitle());
      rootNodes.add(node);
    } else {
      rootNodes.clear();
    }
    if (tree != null) {
      tree.clearInitialState();
      tree.setRowKey(null);
      tree.setSelection(null);
      tree.setIterationState(null);
      tree.setRowKey(FacesContext.getCurrentInstance(), null);
      tree.setData(null);
    }
  }

/**
   * Выбор элемента дерева.
   * 
   * @param selectionChangeEvent
   *          selectionChangeEvent
   */
  public void selectionChanged(TreeSelectionChangeEvent selectionChangeEvent) {
    Collection<Object> selectionColl = selectionChangeEvent.getNewSelection();
    if (selectionColl != null) {
      List<Object> selection = new ArrayList<Object>(selectionColl);
      Object currentSelectionKey = selection.get(0);
      tree = (UITree) selectionChangeEvent.getSource();
      Object storedKey = tree.getRowKey();
      tree.setRowKey(currentSelectionKey);
      currentSelection = (TreeNode) tree.getRowData();
      tree.setRowKey(storedKey);
      isSelectionChanged = true;
      @SuppressWarnings("unchecked")
      AsgeExtendedDataTableModel<? extends AsgeEssence> dataModel = (AsgeExtendedDataTableModel<? extends AsgeEssence>) javax.faces.context.FacesContext
          .getCurrentInstance().getExternalContext().getSessionMap().get("extDataModel");
      dataModel.setSelectedNode(currentSelection);
    }
  }

All is fine until i try to refreshpage - F5 i get the error

15.03.2011 15:10:52 com.sun.faces.application.view.FaceletViewHandlingStrategy handleRenderException
SEVERE: Error Rendering View[/WEB-INF/flows/controlpanel/main.xhtml]
java.lang.NullPointerException
        at org.richfaces.component.AbstractTabPanel.getActiveItem(AbstractTabPanel.java:60)
        at org.richfaces.component.AbstractTogglePanel.encodeBegin(AbstractTogglePanel.java:168)
        at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1641)
        at org.richfaces.renderkit.RendererBase.renderChildren(RendererBase.java:278)
        at org.richfaces.renderkit.html.PopupPanelRenderer.encodeEnd(PopupPanelRenderer.java:534)
        at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:879)
        at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1650)
        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:1643)
        at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1646)
        at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1646)
        at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:389)