overrida page med detta

protected override void SavePageStateToPersistenceMedium(object viewState)
        {
            if (Page.ToString() == "ASP.default_aspx")
            {
                
                string str = "VIEWSTATE_" + Request.UserHostAddress + "_" + DateTime.Now.Ticks.ToString();
                Session[str] = viewState; // session works in web garden
                //Cache.Add(str, viewState, null, DateTime.Now.AddMinutes(Session.Timeout), TimeSpan.Zero,
                          //CacheItemPriority.Default, null);
                ClientScript.RegisterHiddenField("__VIEWSTATE_KEY", str);
                ClientScript.RegisterHiddenField("__VIEWSTATE", "");
            } 
            else
            {
                base.SavePageStateToPersistenceMedium(viewState);
            }
        }

        protected override object LoadPageStateFromPersistenceMedium()
        {
            if (Page.ToString() == "ASP.default_aspx")
            {
                string str = Request.Form["__VIEWSTATE_KEY"];
                if (!str.StartsWith("VIEWSTATE_"))
                {
                    throw new Exception("Invalid viewstate key:" + str);
                }
                return Session[str];
            } 
            else
            {
                return base.LoadPageStateFromPersistenceMedium();
            }
        }