[users-admin] add-user-button inactive / sudo has no permission

[huiii]

i am running ubuntu hardy 64bit and i have this bug now:
i wanted to add a new user.
under "system>administration>users and groups" the add-user button is inactive (gray).
i also cannot change settings of my own account, as if i am some user, but i am THE user..
everything is grayed out. so i could not, by any means add a new user, nor change my own settings.
when launching this application through xterm
$ sudo users-admin
i get following message:
** (users-admin:15450): CRITICAL **: Unable to lookup session information for process '15450'

i was able to create a new user by doing
$ sudo adduser <username> though..
i installed this system fresh one week ago and i did, as far as i can remember, nothing weird.
is there any solution?

[Pedro Villavicencio (pedro)]

Thanks for the bug report. This particular bug has already been reported into our bug tracking system, but please feel free to report any further bugs you find.