I have tried 10.2 upto 10.7 and so far found 10.4 to be the most stable. I have yet to try 10.8 but others have said it caused them quite a few problems. I was wondering if playing at a lower res with crossfire and no vsync may be causing problems. I have fluxuations in FPS between 80 and 160 depending on what is showing on the screen. I have all the graphics settings on the highest they go.