Morning Peter,
This is all very strange, windows environments are a bit of a minefield. I have created a debug version of my driver and passed this to Jared at Main Sequence Software. This debug driver looks identical to the normal driver from the client point of view over the ASCOM API but has all the hardware specific USB communications stubbed out. This allows Jared to install and test the driver without any hardware connected.
I'll be very interested to see what he finds
Cheers,
Dave