Problem solved with drastic solution.
I was having the same experience with this error when I signed in. No problem with Sky Newa etc.
Then 3 days ago a Windows update made it impossible for me to boot up my Windows 10 Laptop. I found an option on the boot menu to make a clean reinstallation of Win 10, saving all myr data but losing any programs in the Program Files folder. Email address book was saved as were Favourites for IE11.
Much to my surprise, having reinstalled Silverlight, Sky Go worked perectly. Programs like Office were then reinstalled. Quite a lot of work but perhaps Sky should advise this work-around.