An OpenDevice() must eventually be matched by a call to CloseDevice().

All I/O requests must be complete before CloseDevice().  If any requests
are still pending, abort them with AbortIO() and remove them with WaitIO().

   if (!(CheckIO(KeyIO)))
       {
       AbortIO(KeyIO);  /* Ask device to abort request, if pending */
       }
       WaitIO(KeyIO);   /* Wait for abort, then clean up */
   CloseDevice(KeyIO);