Hard to say, Ed.
If you have a serial port or USB to serial cable, I would test COM2 on your RRC
to see if it works that way (turn USB CAT off first). That would at least indicate
where the problem lies and make it much easier to solve.
If you can't test it that way, then it will be more difficult to find. You can send me
a screen shot of your COM ports in Windows for a starter. Otherwise, maybe the
RemoteRig guys in Sweden or someone else has something I missed.
73,
Mitch DJ0QN / K7DX