I’ve had my current PC for over 3 years and bought it new with Windows XP Pro. During that time I must have booted it around 1,000 times without problems, Microsoft updates are set to automatically download and install and have done so for over 3 years. Suddenly, yesterday Windows Genuine Advantage declared my installation of XP to be fake.
I went to the Microsoft support site and followed links and articles to a point where I could have an online chat with support. I told them what the problem was and gave my Product Key which they then said ‘has been blocked’. ‘Why?’ I asked only to be told that all they could say was that it was blocked. I told them that I had the original CD and COA which bore the Product Key which had been fine for years. The Microshit response to that was to terminate the online chat. Charming!
Googling the problem seems to suggest that the copy of XP which I was sold was probably counterfeit – it had the hologram on the disk, the fine silver threads in the COA were there but they must be clever fakes.
It appeared that I’d remain with a crippled PC permanently bearing a pop up, which can’t be closed, saying that my copy of XP was fake. In addition to that the desktop is set to be a black background :-( Clicking the link on the pop up wants to take you to Microshit so that you can buy another copy from them, but then it adds that XP is no longer available and they want you to buy Windows 7. Googling discovered that in the past MS would replace a counterfeit copy, purchased in good faith, free of charge but not any more. I’ve got a receipt for the PC and copy of Windows XP from the supplier who no longer exists. I can prove I bought it in good faith but that wont get me anywhere.
So, I hacked XP to not carry out the authentication check when it boots. Various ways of achieving this can be found on the internet but they didn’t work for me. Not one to give up I found my own way to disable the authentication check and now my copy of XP is back to where it was. OK, it wont now be able to receive updates but I’ll live with that.

Matt // Dec 10, 2012 at 00:41
Ditto, but I cracked my XP myself – not that it makes much difference as XP updates/support expires in March anyway.
More interestingly, Win7 can be cracked in exactly the same way, thus rendering all of Microsoft’s genuine advantage “technology” utterly useless :)
MJF.
Southsea