@marko8904 and @b … I was getting the .dwi logs for you off the system that was failing but began working (Arran) using 6946 , and the system that was working on 6896 and failing on e.g. 6946 (Shuna) but now (unfortunately for the purpose of finding the cause !! ) Shuna also has started working on 6946. I am not sure what the change is as I had installed vc_redist.x64.exe on Shuna and rebooted before and that did not clear the issue. But for some reason now that I cannot explain 6946 is also working on Shuna, much like it did on Arran.
One change to the system is that I had installed and then uninstalled HighFidelity-Beta-PR11108 and even though that also did not work on Shuna that MAY have left some changes.
Anyway… in case they are useful I placed the .dwi log files for Arran (6946) and Shuna (6396 and 6496) in a temporary location at http://www.aiai.ed.ac.uk/~ai/EXPORT/TEMP/HiFi/
Dependency Walker did show some errors while running. but these were for all versions, i.e. the working versions as well. But it may be worth eyeballing those.
Let me know when you have those files and I will remove them.