My wife's mother was having trouble with Windows Vista (64 bit). She said that Windows installed a couple system updates, then stopped working. Sure enough, I restored the computer to a previous configuration, got everything working. Then Microsoft installed ten updates again, which completely broke the system. It wouldn't even boot. This took several hours to fix.
Seems like this was a widespread problem:
I think it's awfully suspicious on Microsoft's part, that this broke. Especially since it occurred during the start of the biggest spending week of the year, right before Black Friday. Coincidentally, Microsoft just introduced a new product they are wanting to sell: Windows 7. It certainly would be a clever way to drive up sales of new PC's during the spending spree. If they break Vista and XP, a lot of people would just buy a new computer rather than paying the cost of fixing an old one.
At the very least, there's an inherent conflict of interest in that Microsoft is able to modify software that someone purchased, at the same time they want people to stop using it and buy something else. Since like any company, they assign priorities in terms of what makes the most money. :-)