After reading the message “helloimneil - CV Plugins Possibly Causing X-Particles / Cinema 4D Crash”, I focused my attention on the folder preference. I made a copy of the preference folder and deleted it. When I restarted C4D R20, I was able to log with Cineversity again. After more tests, it appeared that it was, perhaps, enough to delete the “template.l4d” and “template” forms if they are present. Delete also “sketchprefs.C4D”, “sketchprefs”. It may be possible that once you reconnect you need to reinstall some plugins. I did it and everything went right.
If, nevertheless, you must delete the folder preference, keep the files “shortcuttable.res”, “dark.col” for the new preferences folder that will be recreated when starting C4D.
Have a good day