Ok, first things first. Is this install on Win / Linux / what? After you installed MySQL, did you create a password for the MySQL root user? Did you create any users?
Common misconception about MySQL is that because the admin user is 'root', people think that root user is the same as the system root user. MySQL has it's own set of users, seperate from the system you're running on. You can't login to MySQL with the same root password you login to your system with, you have to create a new password for the MySQL root user. I wish the developers would change the admin user name to 'dbadmin' or anything but root.