Are you running a service? I can't say I'm too familiar with the file you uploaded, but the file contains a few things that lead me to believe you may be. As David said, it would be helpful to know what you were doing.
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.