Happy to have helped and thank you for letting us know what resolved the problem, that helps others browsing/searching the forums for a solution to a similar problem.

During the two years that you have been using avast other things are also changing on your system, not least OS updates, additional programs added, etc. sometimes there can be issues. Many times we never find out the true cause, but often members of these forums recognise a symptom and offer a suggestion that worked for others.