I have a i7 Windows 10 computer that had T-Bird V68 installed and working until I updated to version 78. Now I have deleted the account to reset the password and manually deleted all the certificates from T-Bird and Firefox. I still cannot get T-Bird to not generate security errors about the Google certificates. I have uninstalled T-Bird and re-installed and still have the same problem. I added the register to the about:config for the port for gmail but this keeps the ports for HotMail and Yahoo and other mail hosts from working. I have another older i3 computer that I did a fresh install to windows 10 and installed T-Bird. It works fine with all the email hosts for sending and receiving mail using the same email accounts as the other i7 Windows machine. So something in the older registry or other persistent data repository is keeping it from working with Gmail, Hotmail, or any of the other IMAP email hosts.