CreateSwapChainForHwnd returns E_ACCESSDENIED

[EricMao]

First call into a new class succeeds, second call into a NEW class fails using the same HWND.

However, I'm unable to create a new window handle as a work around (CCTV switching in a single HWND).
The error is 'CreateSwapChainForHwnd returns E_ACCESSDENIED' on a second Class and Call using the same window handle.
A believe a DirectX resource / object has not been properly freed.

I believe the issue to be related to the following thread:
https://stackoverflow.com/questions/20556885/directx-11-createswapchainforhwnd-fails-with-e-accessdenied 

And have subsequently called both:
D3D11Context->ClearState();
D3D11Context->Flush();

in the Close() function as recommended by Microsoft to no affect, similar to the stackoverflow thread above.