FYI, I didn't overlook that the crash went away when you added a delay in your Update() method.
It seems to only happen if the static constructor of the AffineThreadPool runs during the first time Update() is called.
Could you try if the crash goes away when you put
int i = AffineThreadPool.Processors
into your game's Initialize() method, thereby executing the static constructor earlier?
Also, I have entered a bug in CodePlex' issue tracker with my minimal reproduction case attached. Can you confirm that it reproduces the bug for you as well?