Black screen again "Windows not genuine"

Hi all - my first posting, and sorry that it's a well worn path - but I still can't understand what's happened, and I hope to get some answers from those more knowledgable than myself, before I start phoning MS or my retailer.

Last December I bought a custom computer from PCSpecialists. I also bought a full, shrink-wrapped retail version of Windows 7 HP via Amazon, for £78 from Yas Stores. I did a clean install, and thought that I'd checked the box for auto online Activation.

I then partitioned the hard drive to provide a seperate volume for my photo files.

Since then, up till 3 days ago, everything was working fine.

Then I got the black screen, the error message 0xC004F200 and an invite to sort it all out online - a process which ended with my being informed that I'd either got a counterfeit, or this copy was being used on another machine. Oh, and did I want to be another copy?

Before I start pestering MS, and/or my retailer, I'm hoping that someone with more knowledge than I have can give me some help. I attach a .txt file of the Diagnostic Report in the hope that it might provide some clues?

I must say, I am an out and out law abiding citizen who would never knowingly buy counterfeit software, and am therefore rather miffed that MS assume you are guilty until proven innocent - and then make the process of proving that innocence as opaque as possible....