yes, I rebooted several times, before and after re-installing the packages.
I have no idea what may be causing the problem, as the system was (and is) running smoothly. Only noticed the freeze when trying to change system settings. That's why I reinstalled a number of KDE workspace related things.
When shutting down there's always an error with rdc.something (will have to check tonight), don't know if that's anything to do with the problem.
After installation of PCLOS in March I had added a number of apps, some widgets, color and plasma themes, the usual stuff, I guess. All from the repos, nothing queer.
I had applied the kernel patch Texstar had posted and found no problems afterwards. Can I undo that patch? It was the only change I made outside Synaptic. I know the patch might affect the network which it didn't in my case. Could it have side effects?