This error was reproducible but I don't know how universal it is because it happened on an ASUS Crosshair Hero VIII motherboard.
After installing Ryzen Master and checking that it loaded, we downloaded and installed the latest WHQL AMD Graphics Driver for his PowerColor Red Devil Ultimate 6900XT.
As soon as that driver was installed Ryzen Master would fail to start with the driver not installed error message.
I then uninstalled the graphics driver and Ryzen Master worked perfectly again.
I then told the person to install the graphics driver but this time to make sure that the checkbox (which you can find under "additional options" before you click on install) Factory Reset was checked.
We loaded the graphics driver and this time Ryzen Master had no problems loading and the graphics driver worked properly.
<humor> This is just Windows way of trying to have a dependency issue like a linux distro.
These fun issue's can happen when software is developed to function on a set driver version or later upon release then trying to roll back to a unsupported version that predates the software. Given time your current version of Ryzen Master will retain what will eventually become residual garbage in the registry that will need to be cleaned up manually when a new version gets install in the future. With an exception should AMD changes it so that it gets cleaned up by an uninstall process prior to installing the newer version. Another probability is that a user will record the settings made in the tool to which they actually take the time to implement the settings in the BIOS itself, thus they will not have to depend on the software after that point. Providing they choose follow the logic of doing this. But this is merely my own opinion and thoughts on software overclocking/underclocking. Cheers 🙂