I can replicate the issue on a few systems with various graphics cards -- all are windows 7. Based on the debug info in the text file it looks like it is drawing a frame on a back buffer and when it goes to flip the buffer to present it to the user for viewing it has no surface to draw on (game lost focus and is no longer active) and as such it crashes. I am sure watching for the game having focus and sleeping when not in focus would resolve the problem. Garbage Collection is also really a problem with the game. It seems like a lot of objects are not being disposed of correctly when no longer in use.
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DebugMessage: Error flipping back buffer to primary buffer.
DebugMessage: Device lost
Debug Message: ResourceManager::Invalidate
