There are three things that you HAVE to do before you install an AMD graphic driver and I think I know the reason why you have to do this.
1) Download the latest WHQL GPU driver. DO NOT DOWNLOAD ANY DRIVER MARKED AS "OPTIONAL".
2) Unplug the PC from the Internet and run DDU (Display Driver Uninstaller).
3) After the reboot and with the system still disconnected from the internet, install the driver and at the opening screen, click on "Additional Options" and put a checkmark into "Factory Reset".
Your AMD driver will now run perfectly.
Until I hit on doing it this way I ran into a number of issues, but since adopting this method I have not had a single CTD, BSOD, or Black Screen in games due to my 6900XT.
The reason why I think this is happening is that AMD seems to be bringing out a lot of GPU driver updates and going from one to the other I think that there are artefacts being left in the Registry that screw up a subsequent installation.
After the DDU one would think that the "Factory Reset" option would be superfluous - BUT IT ISN'T!!
I think that there are things that DDU doesn't catch (even if run in Safe Mode) which the Factory Reset does - and vice versa.