= Why this is happening =====
This is a common problem if you do a mysql import and overwrite the mys... mysqldump -A backup.
This is a good thing: you probably want to back up all your mysql users, permiss... fact, unless you also backed up that file, you probably don't even know what that password is anymore... er, when you apt-get installed mysql-server, it probably prompted you for the new mysql root password
