private void Page_Init(object sender, System.EventArgs e)
{
     TreeView catalogtree = (TreeView)Cache[ "CatalogTree" ];
     if(catalogtree == null || !IsPostBack)
     {
       .... Загружаем дерево ....
      CatalogTree.Nodes.Clear();
      CatalogTree.Nodes.Add(AMCourseCatalogDB.GetTreeItems());
			
      Cache[ "CatalogTree" ] = CatalogTree;
      }
      else
      {
	CatalogTree = (TreeView)Cache[ "CatalogTree" ];
      }

}