It is the latest release 1.4.2.4 [10045] (Official Build)
and there are no error logs on the server.
I have successfully added 7 users to the gallery, but when I try to add an 8th, it says "User name not provided" in a red message that fades away at the top of screen after a few seconds.
If I delete one of the accounts and create another one it adds fine, only the 8th user onwards doesn't work.
Even when I try and register a user through the website itself, it let's me create a new user, sends the email, click the link to activate, and then when I try and log in it just refreshes the page and clears the username and password.
Any ideas?