<t> The exe was allowed to connect to any PC (local and internet) by the firewall already. I tried to modify the rule of the firewall by blocking any connection (for the game exe) but the game did not start (usual error). I tried also to deactivate completely firewall and antivirus with the same ...

<t> Try to start the game after discottening the computer from the LAN (and Internet) ! I had the same problem with the demo and by this way I was able to bypass it. It works (for me) both on windows 7 and windows 8.1<br/>
I have not tried to reconnect the computer to my LAN (and internet) after ...