Installed new KSC Free to replace KAV Free.
Installation OK, restarted and install seemed to complete normally. Responded to main network KSC prompt (allow).
Then a KSC window appeared (something with a “do not prompt for 30 minutes” checkbox near the bottom and Windows froze with no response. Waited several minutes, but system did not respond at all.
Forced reboot. Win10 was broken, unbootable, and automated repair could not fix. Chose a restore point and restored. Chrome would not start, had to uninstall-reinstall.
Alienware Area 51m
Win10 Pro v1909 (build 18363.657)
Best answer by Flood and Flood's wifeView original