Avast pro and Google calendar

Today I installed Avast Pro and found that it is incompatible with Google calendar. For several months I have used the calendar on Thunderbird with Google calendar without any problem. Since installing Avast I can no longer access any of my events via Thunderbird.
I am using Firefox and Windows 7 and am very annoyed about this.
And the fact that the stupid Captcha is going to take me 3 or 4 goes before I get it right.

The captcha is only first 3 posts… spam protection

If you turn off mail shield … does it work then?

If your using Google Calendar why don’t you just use Gmail on the web. Thunderbird is a thing of the past. I use Gmail and Google Calendar with no issues. Been using avast for years.

Avast! IS compatible with Google Calendar. I also use Thunderbird with the Lightning add-on and Google Calendar. It works fine. Something else is happening with your system. Make sure that you have the latest version (2.6) of Lightning and the latest version of avast!.