it looks like this, the distorted pixels are in the left and right corner
it happens again and again, no other sideffects yet.
what to do should i run to a apple dealer and get my board switched,
i know this effect from former slowly and painful dying GPU's
As it turned out the Motherboard was defect.
i let them change it on 06.2012
funny thing is the new board just died again yesterday.
i got the second board just replaced throu a third one. Everything works fine now again.
the problem is in some way connected with the ones reportet here:
many people having a ** GPU Debug Info Start ** in their logs when the problems occure. When i replaced the first board 06.2012 i didn't found any ** GPU Debug Info Start ** messages in the log, the system also was freezing and glitching in another way.
also this bug is hardware related and only fixable by replacing the logicboard eg. the gpu onboard.
hope this helps