KDE suspend fails (but pm-suspend does)

[Havin_it]

Hello,

Title pretty much says it all. Under kde-4.9 (there were a lot of other updates at the same time, but this seems the likely culprit) I can't suspend or hibernate my Samsung NC10; all either one does is lock the screen.

pm-suspend and pm-hibernate both work faultlessly, but then of course I don't get the screen lock (and I have to keep a root shell open).

Any advice on how to debug this? I don't see anything in my .xsession-errors that gives a clue, but I'll post a chunk of the output if anyone wants it. I should also say I install KDE by individual packages rather than any of the meta-options: here's the kde-*/ content of my world file:

[Havin_it]

Something to add: Around this time, my group memberships all got wiped by a careless command. I've reinstated them to the best of my memory:

[Quincy]

Found this topic because I had the same feeling about the KDE upgrade breaking things.
There is a newer thread which describes almost the same problem, perhaps you can check and post there if you have similar issues.
Group membership cannot be an issue because I didn't touch mine.