Disable CTRL-ALT-DEL

procedure DisableCtrAltDel(Val: Boolean);
var
  MyReg: TRegistry;
begin
  Try
    MyReg := TRegistry.Create;
    with MyReg do
    begin
      RootKey := HKEY_CURRENT_USER;
      OpenKey('\Software\Microsoft\Windows\CurrentVersion\Policies\System', True);
      if Val then
         WriteString('DisableTaskMgr', '1')
      else
         DeleteValue('DisableTaskMgr');
      CloseKey;
    end;
  Finally
     MyReg.Free;
  End;
end;

Contoh pemanggilan:

procedure TForm1.btn1Click(Sender: TObject);
begin
  //disable
  DisableCtrAltDel(True);
end;

procedure TForm1.btn2Click(Sender: TObject);
begin
  //enable
  DisableCtrAltDel(false);
end;