For anyone using the rather useful NoMachine NX service to enable remote gui access to a machine theres been an  little problem with Ubuntu Hardy. To do jobs like add users there is an unlock button on the dialog box and when accessed via an NX session this is grayed out. Its down to the “policy kit”.

To work round the policy kit weirdness there are some notes here which is where I finally got my solution

in short, login to a terminal

sudo -s

ck-launch-session users-admin

or if you want o admin services

ck-launch-session  services-admin

and volia the unlock button is no longer greyed out.