UK car insurance company AA accidentally sent out a password update email to its customers, the incident was caused by a human error. The messages led the motorists to log into the motoring organizations website to change their passwords. The concurrent access of a so large number of customers crashed the AA servers, then its customers couldnt access their profiles, believing their accounts were compromised by hackers. The company reassured its customers by confirming that the change password messages were sent out for error.”]
Source: http://securityaffairs.co/wordpress/60458/hacking/aa-password-reset.html