In a post yesterday, company spokesman Villu Arak said the high-volume of restarts caused by Microsoft's updates led to the Skype network being overloaded.
But now Skype wants to distance itself from blaming Microsoft for the outage. In another post on Skype's Heartbeat blog Arak says, "[the reaction] reminded us of one of the basic tenets of communication: It's not what you say. It's what they hear.
"We don't blame anyone but ourselves. The Microsoft Update patches were merely a catalyst - a trigger - for a series of events that led to the disruption of Skype, not the root cause of it. And Microsoft has been very helpful and supportive throughout."
In short (as the explanation is quite lengthy), the mass of PCs resetting not only caused a flood of log-in requests but also "combined with the lack of peer-to-peer network resources" to have "a critical impact".
"The self-healing mechanisms of the P2P (Peer to Peer) network upon which Skype's software runs have worked well in the past," continued Arak. Skype says the problems triggered a "previously unseen fault in the P2P network resource allocation algorithm" which disabled the self-healing nature of the P2P network.
Skype also made it clear that this set of Microsoft Updates was not to blame, nor were they handled any differently to previous updates. "In previous instances where a large number of supernodes in the P2P network were rebooted, other factors of a 'perfect storm' had not been present," explains Arak.
"That is, there had not been such a combination of high usage load during supernode rebooting. As a result, P2P network resources were allocated efficiently and self-healing worked fast enough to overcome the challenge."
Lack of proper explanation
However, the latest post by Arak leaves some questions remaining. There is still no proper explanation for the timing of the outage which occurred last Thursday, two days after the patches were first released.