Testing network interrupts in software
You might want to abstract the network layer, and then you can have unit tests that inject interesting failure events at appropriate points.
The closest I can think of is doing something similar with VEDekstop from Shunra..
Simulating High Latency and Low Bandwidth in Testing of Database Applications
Shunra VE Desktop Standard is a Windows-based client software solution that simulates a wide area network link so that you can test applications under a variety of current and potential network conditions – directly from your desktop.
You can subclass whatever library class you are using to manage your sockets (presumably CAsyncSocket or CSocket if you are using MFC), override the methods whose failure you want to test, and insert appropriate test code in your overrides.