AMD Catalyst News: Radeon Software Adrenalin released for Windows. Available at https

Driver version: 21.20.01.14
More...

Attention! Microsoft is again pushing updates that replace your GPU driver with theirs, which is a non-OpenCL capable one and so useless for crunching.

Use the new driver AMDave reported instead.

I had to go as far as installing the Radeon Pro driver to get my HD 7790 working again under Windows 10...