While the headline of this artilce, WARNING: device driver updates causing Vista to deactivate, by James Bannan, might sound dire and a bit like FUD, it is actually a well reasoned and researched article on a problem any Vista user could potentially experience. Bannan explains why a user might experience an issue where a Windows Activation prompt might alert you that you need to activate your copy of Vista after you’ve been operating awhile.
It turns out that there are some issues relating to devcie drivers and new hardware and how different drivers report back to Windows. The upshot: if you install new hardware (say a video card) or update drivers, you could fall prey to this. Bannan also reports that Microsoft is aware of the issue and is working on a solution. Well worth a read and archiving for future reference.