If you were not aware, Skpye had a significant global outage last week affecting some 220 Million users. It all started as a chain reaction from millions of rebooting PCs that had installed Windows updates. The real culprit, however, was a Skype software bug that affected what was supposed to be "self-healing" P2P network.
From a Skype post: 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.
The company insists that the outage was in no way security related. "We would like to point out that very few technologies or communications networks today are guaranteed to operate without interruptions," says the company.