Changed the type of desktop environment to KDE 4.5.1 from plasma-desktop to plasma-netbook (System Settings->Workspace->Workspace Type).
Stopped working sleep mode when you close the lid when running on battery (System Settings->Power Management->Edit Profiles->Powersave->Actions->When laptop lid closes->Suspend-to-RAM),
as well as the lock screen (pressing with lock does nothing, the shortcut is too).
If the settings return plasma-desktop (no reboot required and Logutov), everything is working properly. As, however, if you do sudo pm-suspend.