Unable to connect to the server.
You're trying to play with someone probably protected by a firewall or by a proxy. If you are not behind a firewall, the best is to join the server, set yourself as ready and wait for a player to ask you to play with him/her.
The game freeze when I'm playing against the computer.
There isn't any solution except restarting the game or waiting for the next update.
How can I play with normal game rules?
If you play against a friend or the computer then the active game rules are those defined in you options. To modify them click on the "Define the special rules" toolbar button.
If you're playing on TCP/IP the active rules are those of the game creator. If you're playing on the WBC server (witch is now Beroux.com) then the rules are those of the player receiving "Do you wish to play with X?".