K - (I know you are frustrated)
BUT you are learning about MySQL -
1st thing- 'system users' (whatever the OS) have NOTHING to do with MySQL users. ALL new MySQL installs, everywhere in the known
Universe, arrive with ONE user 'root' an with no password set. (if you had a cup of coffee, tea, a beer and gave it a thought, or just meditated on that, you would see why - the Zen of MySQL
SO - user 'reg' will have only rights in MySQL someone (or script) defined. Until YOU create new users, (with MySQL itself) - the user you want to work with is 'root'. (this has nothing to do with your current Linux username) So - 'reg' was probably defined by Akonadi (or some other app).
2nd. - The 'Control user' is another matter, its a special entity used by phpMyAdmin.http://wiki.phpmyadmin.net/pma/control_user
Part of the thing here is you have to learn about MySQL (we all do at some point if we want to be able to fix things when they go BOOM!). Real Life Example --Yesterday, I had a brand spanking new Database I had just uploaded onto a production server go POOF! (and disappeared without a trace)
Hours of work getting everything settled in - GONE!
Something I did with a development tool, have not deciphered what yet - must have triggered a 'DROP DATABASE' command (and one without a "ARE YOU FREAKING SURE?" moment...) Fortunately I know that every time I do something major to a database, I export it to a SQL file. (saves the head-smashing on the desk part)
SO I just ''created'' the empty database all over again and used the 207.xx.xx.xx-principal-20101011092045.sql file (made in phpyAdmin) to pour all that back onto the server... ~tada~ you have database!
Some time ago, I decided I 'had' to really learn MySQL - I plunked down (after some searching) for the LinuxCBT MySQL DVD's (was beau coup bucks then) - they offer it online, cheap, now on a monthly subscription basis. The guy is a bit dry, but the man knows him some MySQL. Books are also good, and I have a batch of them too
It looks like your instance of MySQL may need a fixup. If Akonadi created that profile, they probably did a minimal job and it may have been optimized for their purposes. You will need to track down the 'my.cnf' (default name) file from that install (its probably somewhere in /var/) and take a look at it.