After waking up, often the windowing system fails, as I think. The screen shows either only the mouse pointer, or distorted windows, or nothing. There may be some interaction possible with windows, but of no use.
Sometimes, however, waking up from hibernation goes correctly.
Switching to console via Ctrl-F1 works normally. Console works normally. Hibernating and waking up from no-graphics usage works normally.
From the console one can see that process kwin takes almost 100% of the CPU. Killing kwin may show the windows, but the control over the windows is gone. Restarting the X server cannot be done normally. I have then to reboot as the graphics does not work.
I use opensuse 13.1, KDE 4.11.3, latest Nvidia driver.
Next time, instead of killing kwin, press ‘alt’+‘F2’ which will drop down the run dialogue and enter the command ‘kwin --replace’, and see if the cpu usage is still 100%.