First of all thanks for the answer and the observations.
Nevertheless I would like to make to notice that, in the example of before, any other operation done on the file (Test_file.exe) just pasted in the Shared Folder of the other pc, it doesn't produce any error or warning about denied access; I can launch, open or cancel it, I can perform, for example, also a manual scanning with Avast on that file, without any recorded warning.
I agree, however, that this is a tolerable problem: I have only signalled to give my little contribution to the improvement of this already excellent antivirus software.
mec