Domain Admins group login problem

[Magnus Naeslund(t)]

I have created an user called "administrator" and put him in the "Domain 
Admins" group. But i still can't login to an workstation locked by a 
normal user, my understanding is that this should be possible.

I would like to use this feature instead of remotely halting the machine 
via RPC, since i can't shut down any running applications properly that way.

Does anyone have any hints on why this isn't working?
What can i do to diagnose the problem?

Magnus