After installing the Catalyst 11.10 preview (and previous 11.9 preview) drivers for Rage and Battlefield I'm getting consistent crashes when calling ChoosePixelFormat(...) with a valid PIXELFORMATDESCRIPTOR while creating an OpenGL context. This works just fine with the release version of Catalyst 11.9.
I tried many different modes, bit depths, accumulation buffer settings and none of them work when calling ChoosePixelFormat(...) with the preview drivers. Even the OpenGL extension viewer (http://www.realtech-vr.com/glview/) crashes with the same behavior where the driver stops working, the screen goes blank, then restarts.
If you need any other sample code I could post it here.
EDIT: This has been happening on Radeon HD6850 cards (both Sapphire and Powercolor)