Facebook, February 24
For almost three long, painful hours, some users across the world were locked out of Facebook and worried their accounts had been hijacked.
The social media giant later explained functionality meant to guard against hackers inadvertently sent users to a recovery screen that gave the impression someone else had logged into their accounts. Affected users were prevented from immediately logging back in.
Facebook confirmed no actual security breach had occurred.
It was the second time that week Facebook had problems. Days earlier, some people reported they couldn't see their news feeds.