Thanks for your answers :

-- I ran into the same problem with mysqlcc. The easiest way that I found to get around the problem was to change the user_id and password for your main user through the command console. Then start up mysqlcc and delete the default server. Add a new server with your new login information. This fixed my problem anyway.

-- No, there's a bug. Trying to log in with the wrong password crashes MySQLCC. Change the password defined in your server registration before trying to log in again after changing passwords on the server.

but whatever user and password I create and use (and the password IS NOT wrong), it still hangs. The only thing that works is reinstalling MySQL after manually deleteing mysql management base.