Hi Jack,
One solution would be to subscribe to SKY X Camera add on as this will allow autoguiding as well as imaging to work at the same time. I use Windows 7 with SKY X pro but use Astro-Physics driver and MaximDL for autoguiding which I have found to be more accurate than PHD. This makes sense for me as I have AP 900 mount and APCC control software, this driver will allow multiple fnctions to work.I notice that the SKY X driver uses version 10.2.0. The latest version of SKX is 109.5.0 Build 11360 I canot see why this should make any difference.
Do you have Microsoft .Net installed?
Clear Skies
Nick