Said Villu Arak on the "Heartbeat" bog today: "The disruption was initiated by a massive restart of our user's (sic) computers across the globe within a very short timeframe as they re-booted after receiving a routine software update."
A "flood" of login requests collided with a lack of P2P resources and "prompted a chain reaction" that caused the downage.
Skype's P2P network has a "self healing" function but a software bug stopped it from working fast.
He said: "We can confirm categorically that no malicious activies were attributed or that our users' security was not, at any point, at risk."
Here's the bog. µ