My legit activation went bad months after Win 7 was installed on my laptop computer, that was shipped with Vista. I bought the upgrade to Win 7 when it was offered to many in the summer of 2009, for $49. It arrived in Nov 2009, what I thought was almost a month late. Then, I decided I wanted more features, so I went the Anytime Upgrade route in Dec 2009.
Everything was cool until I voluntary accepted the KB971033 update, after which I had a black screen, and a notice that I may be a victim of software piracy, or similar wording. I was thinking WTF, my install was legit, and I still have my Vista COA & reinstall discs, plus my receipts for my Win 7 upgrades.
After spending 2 hours on the phone with MS, things were straightened out. They said that normally it wouldn't take so long, but that update was just released (KB971033), and there were more calls than normal.
BTW, the same thing happened when MS decided to start this anti-piracy deal with XP in 2006. I had to call and get that taken care of too, but it took much longer, like 4 days. There were some serious bugs in the system when WGA was introduced.
No big deal, it's just that for the amount of money that Windows OS's costs, these kind of mistakes aren't expected on a massive level.