Following your hints, I’ve uninstalled the avast! Endpoint. After that, the system started in normal mode properly (so, the error was in avast?).

Then I’ve reinstalled the Endpoint (and ran a complete scan) with success.

After that, I’ve repeated the FSTR64 execution (I attach the results).

Please, could you have a look on them in order to confirm if in your opinion everything is solved at all?

The browsers seems to be ok, not showing pop-ups, nor unwanted ads, neither redirecting to akamaihd webpages. But any inspection from you will be welcome.

Thank you very much!

PS.- If solved, I will start sending the logs for the second PC infected, if you don’t mind…