SD: Correct re. 127.0.0.1 in hosts file...I had a Senior Moment.
There aren't any entries for avast.com
Pinging download724.avast.com resolves to 75.126.120.205
download649.avast.com resolves to 74.55.53.82
Turning off the firewall doesn't crack it. With it running, the activity log registers nothing re. the Avast updater - neither permission or a denial of access.
Updater attempts generate nothing in the Event Viewer logs.
Avast is the only resident protection; I use the others as periodic scanners/browser protection.