system
5
I am completely guessing now, OK?.
When I use the right-click menu to scan a middle-size file, Avast shows me the result. But if you select a file like an “installation file” (say, LibreOffice installation executable), Avast would display some details about the process, until finally I get the results.
My guess, if that tray message was indeed from Avast, is that Avast was taking more time than usual (in your system) to finish the scan, so it (Avast) decided to show you that it wasn’t “dead” (it was still active and scanning). Because of some optimizing (cache, just for one example), the next time you tried the scan, Avast was already faster, so it didn’t need to display “I am not dead, and still working”.
Again, just a complete guess.