It seems that a routine software upgrade knocked out 80% of the UK govt. PC’s at the Dept. for Work and Pensions. Though the article mentions Microsoft and EDS, it does not mention the real reason for the issue, just says that “Staff at the DWP found that they were unable to use their desktop computer after a number of technical glitches knocked out 80,000 of the department’s 100,000 terminals.“
Update: The Independent reports that is was only 40,000 machines and says the experts are still baffled as to the real issue. I personally probably trust the Independent more! If you want you can read all the related stories.