Sorry to update the thread dated a month ago but I was intensively working till 2 days ago.
An hour ago I tried launching Calibre from my Windows 10 (home - licensed) 64bit automatically upgraded but the program never loaded. In the Control Manager the process appeared just for a fraction of a second then disappeared. I uninstalled then reinstalled various versions but nothing worked.
The thing that solved my problem was go to safe mode then restart Windows 10 in full activity mode. Maybe the IoBit MalwareFighter and the Comodo Firewall upgraded at the full restart.. I don't know.. I know that Calibre finally launched
Just telling for reference
'bye!