The CM3 is a relatively simple device in terms of the communication between the driver on your PC and the device over ethernet. Once communication is established, and the channels set up, the CM3 will transmit data back in a UDP packet as it converts the channels. Additionally every 3 seconds the driver will check that it has communication with the device by asking if it is alive and expecting a response. My guess would be either the request, or the response, is going missing.
I would suggest putting a packet sniffer, such as Wireshark, on the PC and look at the data flow to/from the CM3.