Leap second: Linux can freeze
The leap second that was inserted on Saturday night can cause permanent high CPU loads on Linux computers. Among other examples, the behaviour is documented in the blog of the Mozilla Foundation, where strange peak loads on one Mozilla server were observed from the time the leap second was added. The developers said that the problem is easily solved by resetting the date or rebooting the system.
Leap second: Linux can freeze - The H Open: News and Features