Ok Mel,

Now we are on track here. I understand fully what you are saying. Yes, a trojan will infect as you said.
What were the names of the trojans that the other AVs found on your system?
I would like to check to see if they are listed in the database file that Avast uses.

If they are not, then we need to get Avast Support Team involved here. If they are, then we need to look further into your Avast setup.

Ok? If Avast is not identifying the trojans, then this is of concern to all of us out here.

:-\