A more general version that can also fix Office, Microsoft 365, and other Outlook problems can be found here. Currently, you can't use Outlook on Windows to edit calendars that are shared with your Outlook.com account, even if you've reconnected your Outlook.com account to Outlook. We're working to make it possible to edit shared calendars in Outlook 2016 for Windows. We are aware that some users may not be able to receive email from Gmail accounts.

Uninstalling this part of your virus scanner is strongly advised