I give it half an hour before the wall falls down . <| sep |> yeah , that ' s an old , old problem , dating back maybe a good 10 years . I can ' t remember if you needed to turn the pad back on after disconnecting it for it to crash , but yeah , it was always something to do with that . I had it ' fixed ' at one point so that it didn ' t crash and wipe out the cfg entirely but IIRC you would lose your mapping for the pad that was removed disconnected as it no longer existed at the point of exit but it seems whenever the code was touched next the fix was removed and we were back to crashing . In the end it likely comes down to MAME not really allowing live hotplugging removing of devices , which , with wireless pads etc . has become an increasingly common scenario software needs to support . The persistent controller ID stuff that was recently added might help make coming up with a good implementation easier at least .