May1st - Can not login / stuck at loading screen following the 1 hour update

There was an 1 hour server shut down on Ocean - Arugal server following the Cata Pre-Launch expansion.

Following the downtime, I was unable to properly login to the server and access the account.

Upon following the login step until retrieving to the character selection, the top bar is showned to be half full and not proceed after.
Managed to select creating a new alliance character, but no further steps were possible.

I have deleted all addon, restarted the computer, minimize all graphics setting etc.

What can be done?