Yeah..something is off.
So I did the install of avast! 4.8. It started a scan by itself. I figure that is a full scan.
Scanned count: 8709
Infected Count: 0
Task name: Resident protection
Run time: 1:23:10:20 (and counting)
OK now just one thing.
You are running the computer and using it as we speak. If that is the case then to see this scan you mention you double clicked the little a spinning icon in the bottom right corner. See attached picture bellow.
There is nothing to worry. That is not a scan per say. You wi'll see a series a other scanners on the left side of the window. Well these scanners serve as an active part of your anti-virus.
The standard shield is there to scan files you open so as to prevent a virus from starting and preventing the infection rather than letting it infect you and then trying to remove it. It is one of the best features of Avast.
The web shield protects you when browsing the web. It scan the web pages you load and if it sees something suspicious it gives you a warning and stops you from downloading the virus onto your computer.
The other Shields are self explanatory.
You will see a cursor with the option of sensitivity. Mine is set to high but most avast users set it Normal considering that this is the best combination between performance and security. That's up to you.
Just reply to make sure that we are thinking of the same thing.