[arch-general] shutdown problems

[G. Schlisio]

hi all,
since a few days, i experience some problems on shutdown. i'm running 
kde and systemd on a fully upgraded system.
when shutting down via kde controls (ctrl-alt-del oder button), i am 
logged off and presented the login screen, but no shutdown occurs.
i tried to change the shutdown command from '/sbin/shutdown -h -p now' 
to '/sbin/shutdown -h now' but that made just no difference.
if i use these commands on bash, it shuts down as expected, not showing 
the login screen.
is this somewhat systemd-related?
hints appreciated…
georg