First, .net 2.0 is required to run HS 2.1.xx. This new version (which is actually still in beta, but MUCH more stable than the 2.0.xx versions, at least for me) requires it.
As for finding the 2414S, I would first try a different serial port if possible. I had to move mine once, as I have 4 serial ports and it just didn't like one of them. Also, be careful about using serial to USB converters. I've had bad results with those in general although some have them working fine.
If neither of those things help, I would go to the Insteon forum on the HS board and ask the developer, Jon, for help. He seems to be able to resolve just about anything.
Good luck!