The application consists of three processes: Process A provides a web interface to the remote user and watchdog services for process B, which A creates by using the multiprocessing module. Process B does the real work and provides a GUI to the local user. Process A communicates with process B via the xmlrpclib module. Both A and B are python processes. Process B uses the subprocess module to start process C, which is not a python process, and it communicates with it using the xmlrpclib module. Process B is the one that crashes every now and then when sys.exit is invoked.

I will try to produce the smallest possible application I can that still suffers from the problem and I will upload it.