Microsoft's Windows Server Update Services (WSUS), used by businesses and big and small to patch Windows machines, inadvertently deployed Skype to a number of desktops this week. Microsoft started to list Skype version 5.9 on its Windows Update service earlier this month, but the application is supposed to be an update version for machines that already have the voice and video service installed.

Machines configured to use WSUS updates without explicit administrator approval were caught by the issue in the early hours of Wednesday morning this week. Microsoft has since marked the update as expired to prevent machines from installing Skype automatically, but a number of Windows administrators have been left having to remove it from affected workstations — a frustrating experience judging by the comments left at Microsoft's support forums.