Please never say again that you have never encountered such situation.
It has been reported by many people, but they used different sentences for the subjects.
Hi,
well in general if we haven't seen it before or we are not able to induce it we are practically blind and without a log files from the affected machine we are not able to do anything.
So please, if you are able to provide us with logs, please do so, because otherwise we are not able to help you.
You can simply send them by executing our log collector utility from this path
C:\Program Files (x86)\AVAST Software\Avast Cleanup\tulogcollector.exe assuming that you have still Avast Cleanup installed on your computer.
Just please add your email address there so we can join the logs with your report here.
Thank you.