From what I understand CloD runs on .NET4.0, and uses unmanaged calls to the DirectX API.
I would guess the reason why you have got issues is because of the WinRT layer in Win 8 which prevents direct access to the hardware. Win 7 does the same thing but the Win 8 layer is a complete rewrite to cater for Metro apps.
strike through =>
If CloD was a COM only based app it should run on Win 8 like IL-2 1946 does, but because its running on .NET, Win 8 may be trying to force it to go through WinRT, and it wasn't written to do that.
Actually just had a closer look at Win 8 Desktop Application Development model and I can't see why it shouldn't work, because WinRT is only for Metro apps. I would guess that CloD has some weird / non standard code that is causing issues on Win 8.
I'm only guessing mind you
But like Alpha said, it is a preview after all.
It is interesting that when MS mentions development for games in Win 8 Metro, they talk about 2D and basic 3D apps using C#, VB with XAML.
But for DX 11.1, it's C++ and HLSL only. This might confirm that Direct X will remain an unmanaged API, and probably fuel the rumors that XNA is being phased out.