Amnesia Turns Black and System Locks Up

[HotSherlock]

I'm trying to run Amnesia: The Dark Descent, and I keep running into the same issue. The screen turns black, the audio cuts out and my system locks up except for keyboard inputs. With some alt-tab magic I can kill the process, but things like ending the task from the task manager don't work. I'm using a desktop with Windows 7 64bit and crossfired graphics cards. So far I've tried: updating my drivers, turning off vertical sync, uninstalling Avast, matching the resolution to my standard desktop resolution. hpl.log file is attached.

-Edit-
I just managed to get it to run long enough to play a bit and now there are a bunch of errors showing up in the log. New log file is attached. My best guess right now is there's some corruption in my game files. I'll try a full reinstall and see what happens.

-Edit-
No luck. It ran longer but still crashes the same way. I can't find any programs running that would interfere and cause this behavior.

-Edit-
I've tried some new things and am still getting nowhere. I've tried turning off crossfire(thanks for the suggestion jens), disabling the Steam overlay, running windows updates, more graphics updates, and running in windowed mode. The application now lives through whatever was killing it but not by enough to make it playable. New behavior in windowed mode: application window flickering almost constantly; camera moving without mouse control; getting stuck between rooms within a cell; Amnesia icon on Windows taskbar disappearing and reappearing as if the application was being closed and reopened rapidly. I managed to play through the Archives and shut the game down via the menus so my log file is complete now from initialization to exit. New version is attached.