<p>Microsoft has admitted a dodgy firmware upgrade cooked its servers, knocking its Hotmail and Outlook.com email services offline for 16 hours.</p><p>In a postmortem examination of the disaster, the Windows 8 giant said a software upgrade for its data centre equipment - an update that had worked successfully in the past - failed unexpectedly on the afternoon of Tuesday, 12 March. The cock-up resulted in a "rapid and substantial temperature spike" in the hall housing the websites' servers.</p><p>Microsoft did not say in which of its many data centres the machines were based. The company's online storage service Skydrive was also affected but brought back online faster than its web siblings.</p><p>The Hotmail and Outlook.com rack-mounted computers weren't the only systems getting hot under the collar: irate users vented on Twitter their displeasure at being unable to access their emails for nearly a full day.</p><p><a href="http://www.theregister.co.uk/2013/03/14/microsoft_hot_servers/">Keep reading...</a></p><p>Read also:</p><p><a href="http://www.pcworld.com/article/2030777/microsoft-fixes-hotmail-outlookcom-glitches-that-caused-outage.html">Microsoft fixes Hotmail, Outlook.com glitches that caused outage</a> (PCWorld)</p><p><a href="http://www.datacenterknowledge.com/archives/2013/03/14/heat-spike-in-data-center-caused-hotmail-outage/">Heat Spike in Data Center Caused Hotmail Outage</a> (Data Center Knowledge)</p><p><a href="http://techcrunch.com/2013/03/13/the-great-hotmail-outlook-outage-of-2013-continues-as-downtime-passes-12-hour/">The Great Hotmail, Outlook Outage Of 2013 Continues As Downtime Passes 12 ...</a> (TechCrunch)</p><p>Explore: <a href="http://news.google.com/news/more?ncl=dy6qbelJbVENWSM8Uq29Rn_-_-lPM&ned=us">63 additional articles.</a></p>