"But I'm Not a Pirate!"
That cash you just dropped on a Vista license, or the larger chunk you spent on a new PC could get your copy of Microsoft Windows XP or Vista flagged as a pirate version, cutting off its interactive capabilities. If you just purchased a PC or OS upgrade, hang on before setting it up until this situation gets resolved. Or install Linux in the meantime...
DRM bites again: the Microsoft Windows Genuine Advantage servers (which every XP and Vista install phones home to) all failed sometime earlier today.
The result? Every single Windows XP and Vista installation -- except possibly those with volume license keys -- is being marked as counterfeit when it tries to check in. Installations which are flagged as counterfeit switch to a "reduced functionality mode" which results in features like Aero and DirectX being disabled.