“avast 8.0.1497 was released before Windows 8.1” : inexact, August 2013 is before September 2013
http://en.wikipedia.org/wiki/Windows_8.1
https://forum.avast.com/index.php?topic=133824.msg983866#msg983866

I will seriously consider your advice to use a more recent version of Avast
as soon as you have answered any of the question I asked :slight_smile:

Maybe a passer-by is using Avast 8.0.1497 on Win 8.1 64 bits has any experience to share?