Microsoft pushed out a bad update to its Security Essentials software, crashing Windows XP machines and underscoring the fragility of the Windows XP ecosystem. An update to Microsoft Security Essentials, the software company's free anti-malware software, crashed Windows XP computers last week, causing business disruptions to customers still relying on the outdated—and, in many cases, now-unsupported—operating system. The update caused a variety of Microsoft operating systems to restart and then fail to reboot, displaying an arcane "MsMpEng.exe application error" message, according to online posts by affected users. More here