In the end i've been lucky : noticed the web protection issue today, followed the suggested solution and went on reinstalling MBAM and felt really worry when couldn't validate the license.
After a couple of reboots everything went fine, but let me tell that it was just why it appened meanwhile the issue was been solved. Otherwhise i wouldn't have konwn what to do.
Sorry to underline that solving problems unistalling, reinstalling and rebooting doesn't seem really professional.
Furthermore, i had the same problema a couple years ago with an old pc running windows xp but after a bunch of mails with the tech staff, in the end i gave up.
Dardone