New user. New to OMV. New to everything. Missing menus.

Hi all. I am taking my first steps into OMV so please be gentle.

I have a HP N40L server with just one 250GB HD (for the moment) that I am installing OMV onto. I have installed OMV from a USB stick and the process seemed to work well. I logged into the webGUI and it all seemed logical (though I obviously have a hell of a lot to learn judging by all the options!).

The first thing I did was to change the password from 'openmediavault' to something private.

I then logged off, and logged back in with the new password. It lgeed in without a problem, but now all my menus/options have gone from the left hand pane! All that is left is:-

Access Right Management/
User

Information/
Donate
Support
About.

That's it. What has happened?

I must be confusing myself.

I tried logging in with username of 'admin' and password as the one I set up and it works fine again. I thought I had to log in with username 'root'?!?