Windows Patch made Skype crash

The widespread failure of Skype's Internet telephony service last week happened when millions of Windows users tried to log in to the system at the same time, after downloading a software update from Microsoft and rebooting their machines, Skype said Monday.
Users encountered problems logging on to Skype's VoIP (Voice Over Internet Protocol) service early Thursday morning, leaving them unable to connect until Saturday. Skype said that the load placed on its system as computers rebooted after receiving a routine set of patches from Microsoft's Windows Update service revealed a previously unknown bug in the Skype software.
According to the sources, although the Skype network has a built-in self-healing function, the bug within the network resource allocation algorithm prevented the function from working as designed.
Skype has identified the bug, which was a design error and not caused by hackers. The company has already introduced "a number of improvements" to its software to help resolve the problem.