Just got off the phone with Avast Tech Support. It might be an isolated anomaly or a transient anomaly. We recovered full functionality by uninstalling the application and reinstalling it. The reinstall included the same virus definitions that I had updated earlier tonight before the problems occurred. I do not think it is an issue with the file; maybe it was a cosmic ray (just kidding).
Firewall is On and the system is running as before. I recommend you try that or call the team to help you: 1-844-340-9251
Thank you for this advice. Unfortenelly I can’t call, 'cause I live in Brazil, so it’s quite impossible to call to the support.
Besides this, i’ll try to uninstalling application and reinstalling it.