Xbox Annoyance #010. Microsoft is currently "investigating" an issue afflicting Xbox Live accounts, specifically those tied to expired email addresses, according to GI.biz. It seems certain email services, which are set to expire after a certain period of disuse (see: Hotmail), are taking their linked Windows Live IDs with them into the internet's graveyard.
Once the email account has perished, the player's Gamertag also ceases to exist. GI.biz notes that the problem exists among "a relatively small percentage of users," the only solution currently being the creation of a brand new Gamertag. That's one with a pitiful "zero" Gamerscore, by the way.
We expect Microsoft will receive quite a few angry emails about this problem -- probably from Gmail addresses.