I'm posting this in the hopes that it will speed up the resolution of the problem for others, and hopefully help AMD to eliminate the problem from future drivers.
This morning my PC was running Windows 10 64-bit (Pre Anniversary Update) and Crimson 16.9.1 drivers. I had no problems.
As I have a metered Internet connection at home, I brought my PC into the office to do a bunch of updates.
The Radeon App was popping up a toast to notify me of the new drivers (16.9.2), but I knew I had to do the big update to Windows 10 Anniversary, so I did that first.
First boot after the update seemed fine, so I decided to do the driver update to 16.9.2. The update completed, but upon rebooting I ended up with a black screen with only the mouse cursor visible (which I could move around). My power options are set to Shutdown when pressing the power button, and a momentary press did shutdown the PC.
I rebooted a few times, but ended up at the black screen with mouse cursor each time.
I then booted up from a Windows 10 Recovery USB and did a system restore and was able to get into Windows 10 AE again. I used DDU to remove the Radeon drivers. Thinking that the update may have been the problem, I downloaded the 16.9.2 driver and reinstalled. This time after rebooting I ended up with the Windows 10 spinning circle of dots, and could not get to the desktop. The PC would shutdown each time with a momentary press (It never required the power button to be held down).
I repeated the process of booting from a recovery USB, doing a system restore, removing the driver with DDU, and installing 16.9.1 (which had worked before the Anniversary Update), but this had the same problem as 16.9.2
I have now installed 16.7.3 and my PC is working again. I have run a few 3DMarks to confirm everything is working, and the scores are where they are supposed to be.
My system hardware is as follows:
Alienware X51 R2 (i7-4770, 16GB RAM, 500GB Samsung 850 EVO SSD)
AMD Radeon R9 270 2GB (Reference blower type card supplied by Alienware)
If there is any other information that would be helpful, then let me know and I will post it or email it.