Status 3006 is typically a secondary error, caused after a network failure drops the connection. This is common if the PC is not being used for a long time, goes to sleep (or puts the NIC to sleep), and when it wakes up, the server thinks the client is long gone. Sometimes this can be addressed by enabling Auto-Reconnect on the Server and PSQL Client, but not always. You may have to disable power management on the PC (or set to high performance) instead.

Another possible issue is with some PC's (especially from Dell) and RealTek network cards. Microsoft released a faulty driver for various versions of Windows for the RealTek NICs, and I have seen these cards cause endless problems with exactly the symptoms you mention. Swap out the NIC or upgrade the driver to one from RealTek's web site, and this problem goes away.

It might be helpful to confirm the exact exception, too. Check the Windows Event log and post the complete message you see from the software exception. The exception type, module, and location may be beneficial in determining what is going on.

If all else fails, monitoring a PC's connection with Wireshark can yield information about what is truely happening under the covers….