type
  TIsPwrShutdownAllowed = function: WordBool; stdcall;

procedure PowerOff;
var
  h: integer;
  P: TIsPwrShutdownAllowed;
begin
  try
    if not IsWindowsNT then
      Abort;
    h := LoadLibrary('powrprof.dll');
    if h = 0 then
      Abort;
    try
      Pointer(P) := GetProcAddress(h, 'IsPwrShutdownAllowed');
      if not Assigned(P) then
        Abort;
      if not P then
        Abort;
    finally
      FreeLibrary(h);
    end;
    ExitWindowsEx(EWX_POWEROFF, 0);
  except
    ExitWindowsEx(EWX_SHUTDOWN, 0);
  end;
end;