[CLOSED]OpenGL compositing (the default) has crashed KWin in

I am getting the attached message since installing a bunch of upgrades. Not sure what is the cause though, and I don't recall the system crashing. But, since those updates a few weeks ago (I just recently installed Mageia 3, hence various things needed updating) two things happened. I am getting the attached message concerning desktop effects and cannot now mess around with them (but I could before), but also: the screen dimmer on my laptop ceased working. I still get a dimmer bar on screen when I press the appropriate keys, but the light intensity does not actually go up or down, even though the %nrs do.
Concerning the desktop effects though, no response I choose helps, it always keeps getting back to this error message.
Any tips? :s
Concerning the desktop effects though, no response I choose helps, it always keeps getting back to this error message.
Any tips? :s