Thanks Craig !
The registration issue was due to a wrong setup for Avast8: my UI was black instead of white and the registration panel did not have the registration with email feature, only insert file and activation code.
So I uninstall Avast once again, downloaded another setup for Avast8RC2, installed it, and this time, it worked! And so far so good, internet is working with all avast shields up.
Thanks for you help,
Cheers,
Tom.