Ok, solved it.
You need to uninstall the AMD drivers completely (device manager -> graphics card -> driver ->uninstall), and then install it again.
This is a longtime failure in the way AMD drivers update when you do not properly run a totally clean install. You must do it all over. Completely remove every trace of the current driver and CCC. Tell the Windows Device manager that the GPU is removed. It will cancel the driver, but it isn't thorough enough. Obtain and use a product such as Ccleaner to remove every trace from the Windows OS' Registry.
Then, and only then, install a fresh Radeon driver set.
P. S. There are numerous version flags within the Catalyst software; for whatever reason a very few games are looking at a particularly obscure location that normally just doesn't matter. That's what has happened here.
