The Windows Genuine Advantage servers, used to validate your Windows install, are down. Unfortunately, if you can’t reach them, WGA assumes you’re a software pirate and deactivates.

Under XP, this prevents software updates. Under Vista, once you’re marked invalid, rebooting will disable OS features, including the Aero Glass user interface that was one of the flashiest features. And you can’t get any of it back until they fix the servers, which have been down for about 12 hours now. I don’t know what it does to Office…

Meanwhile, MS tech support has been terribly confused, giving out advice that assumes you’re an idiot or a pirate. They seem to be getting the word now, but some of them have told users to try again on Tuesday (!).

Some people are assuming that nobody’s working on it, because Microsoft is closed on weekends. WGA PM Phil Liu responds.