protected void LogOut()
    {
        Session.Abandon();
        string nextpage = "Logoutt.aspx";
        Response.Write("<script language=javascript>");

        Response.Write("{");
        Response.Write(" var Backlen=history.length;");

        Response.Write(" history.go(-Backlen);");
        Response.Write(" window.location.href='" + nextpage + "'; ");

        Response.Write("}");
        Response.Write("</script>");

    }