I've experienced the "display driver stop responding and have recovered" and black screen a couple times on my HD 6870 and 5850's.
For me, it had to do with the card jumping between the 2D and Idle clock speeds. I get this problem most of the time when running a browser-based Java applet or some kind of Adobe Flash content. On the new cards, the idle speeds are too low for 2D stuff, so the drivers freaks out. This problem doesn't happen on my older Radeon HD 4850 becuase the speed only drops down to 500MHz core / 750MHz Memory (3D speed is 625/933) [vs like 175 / 300 on the 6870 / 5850's].
Do you have your game running in Windowed mode or full screen? Windowed mode can cause your problem. Also, what programs do you have running in tbe background?
Things you can do:
1. go into the regestry (regedit) and disable ULPS. http://www.overclock.net/t/667144/crossfire-disabling-ulps
2. Make / change the idle and/or 2D clock speeds with MSi Afterburner.
3. Disable Hardware Acceleration for Flash content.
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