public enum ShutdownEnum
        {
            Hibernate =  1 ,
            Suspend =  2 ,
            Shutdown =  3 ,
            Reboot =  4 
        }

        public static bool ShutdownSys(ShutdownEnum i)
        {
            bool reb = false;
            switch (i)
            {
                case ShutdownEnum.Reboot:
                    reb = true;
                    break;
                case ShutdownEnum.Hibernate:
                case ShutdownEnum.Suspend:
                    return Application.SetSuspendState((PowerState)i, false, reb);
            }
           // Microsoft.Win32.SystemEvents.SessionEnded ??????
            return false ;
        }