Initially this was a nightmare as I previously reported as C11 runs on W10 OS and I had all manner of problems attempting to install C11 Pro (from 8 Pro) because I had to upgrade from W7 to 10.
In order to potentially save others similar grief it transpired that the fundamental problem was that my BIOS was out of date. I built my DAW PC some years ago based around an ASUS Fatality 970 Performance motherboard as that was the only one then that would accommodate the 8 core processor and 32Gb RAM needed for orchestral pieces that I am working on.
To their credit, Microsoft were very helpful in resolving this problem and C11 is now up and running and my PC considerably more stable.
Having said that: I shelled out on Dorico 3.5 but am still having the same “InstallFiles.cab” corrupt or missing problems I had with C11. Also: I now appear to have a very expansive library which, thus far, I am unable to access so a lot of my music is now lacking instrumentation. I suspect this is just a matter of locating it in the right place so C11 can ‘find’ it - which is today’s primary task!
All that aside, thus far I’m finding C11 a definite step up from 8.