Many thanks again for your replies. I think that AVAST! is an excellent programme. I have no complaints, only a question.

I have the feeling that it is not me who misunderstands the programme settings in AVAST!, but the people who reply who are misunderstanding (or evading?) the question I am asking.

Let me re-state the question: is there a setting in the programme that, for example, allows one to exclude all .mpg files on all drives on a given computer from scanning? Yes or no?