KDE power manager goes dead

[Gabriel_Blake]

Hi.

I have no idea what I've done wrong - maybe a system update or a kernel update - but KDE lost all power control features on my laptop. I can add all of them in settings, but they do nothing. Here are some of the things that are broken:
- no action on lid close/open
- no response after resume after sleep (system hangs up)
- no response when ac plug is removed or inserted
additionally:
- screen brightness does work although when changed too rapidly the back light goes crazy and starts to flicker
- sleep does work... but waking up doesn't

Any hints what might be the problem ?