PowerdownAfterShutdown

I have had to reinstall NT 4.0 WS on my optiplex gx1, since I have done so the machine will not “power down after shutdown” correctly. I went into the registry and made the appropriate changes to the “PowerdownAfterShutdown: reg_sz 1” which added the option but, when it powers off it will power back on. I did a little research and found out there has been similar problems with Compaq laptops and NT’s HAL. I would like the machine to shut off completely. Can you tell me how to make it do this without pressing the power button?