This morning Skype released a statement explaining its two-day outage last week - and pinning the root cause on a routine Microsoft update to the Windows operating system that caused masses of users to reboot their PCs at the same time. In an interview last week, Skype’s chief security officer said he did not think that Microsoft had anything to do with the service’s collapse. Skype engineers must have subsequently decided otherwise. Bear in mind that the eBay-owned Skype is not blaming Microsoft. An old, undetected error in Skype software made it more difficult for the system to handle the waves of users trying to sign back on after they received the patch and rebooted their machines. Here is Skype’s full statement: On Thursday, 16th August 2007, the Skype peer-to-peer network became unstable and suffered a critical disruption. The disruption was triggered by a massive restart of our users’ computers across the globe within a very short timeframe as they rebooted after receiving a routine set of patches through Windows Update.The high number of restarts affected Skype’s network resources. This caused a flood of log-in requests, which, combined with the lack of peer-to-peer network resources, prompted a chain reaction that had a critical impact.Normally Skype’s peer-to-peer network has an inbuilt ability to self-heal, however, this event revealed a previously unseen software bug within the network resource allocation algorithm which prevented the self-healing function from working quickly. Regrettably, as a result of this disruption, Skype was unavailable to the majority of its users for approximately two days.The issue has now been identified explicitly within Skype. We can confirm categorically that no malicious activities were attributed or that our users’ security was not, at any point, at risk.This disruption was unprecedented in terms of its impact and scope. We would like to point out that very few technologies or communications networks today are guaranteed to operate without interruptions.We are very proud that over the four years of its operation, Skype has provided a technically resilient communications tool to millions of people worldwide. Skype has now identified and already introduced a number of improvements to its software to ensure that our users will not be similarly affected in the unlikely possibility of this combination of events recurring.The Skype community of users has been incredibly supportive and we are very grateful for all their good wishes.