When creating a "New" tcpClient after upgrading from .Net 1.0 to 2.0 in a console application  I got the error message "configuration system failed to initialize". It was related to the config file I was using.

Although this is not my solution it is one that I have needed quite a few times, especially when moving Virtual Machines and reconfiguring the network cards. Also handy if you install new network adapters.

How to remove hidden network adapters