This seems to be the opposite problem most people ask with KDE PM. I have a laptop running Ubuntu 12.10 and KDE 4.10. After the last couple of updates (I'm not sure which one), my screen stopped turning off after the power management timeout has been reached. This occurs with no screensaver, basic screensaver, or any of the others. It does seem to work the first time after a fresh boot.
Does anyone have any ideas about things I could check to get my screen to turn off?