Microsoft has yet to pin down the cause of the DNS error.

CNN: Microsoft Web sites suffer large scale blackout

In fact, pilot error is the leading cause of commercial airline accidents, with close to 80% percent of accidents caused by pilot error, according to Boeing.

BBC: How human error can cause a plane crash

"The cause of the accident was that the signaller raised the barriers in error when the train was approaching and too close to be able to stop before reaching the level crossing, " the report said.

BBC: Jane Harding

Investigators blamed pilot error, the same cause of two previous accidents.

CNN: How to Repair a Carrier

But a preliminary investigation indicates that typhoon-force winds, not pilot error, was the main cause.

CNN: How to Repair a Carrier

Human error is the most likely cause of an accident.

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It was simple human error, the single most common cause of computer errors.

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Barker and Phillips studied data obtained from the death certificates of people who died in hospital settings between 1979 and 2006, culling those for which medication error was listed as the primary cause of death.

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Over time, as driverless cars dramatically reduce human error (which is the No. 1 cause of accidents) and more people accept the concept of shared cars, the possible car designs will explode.

FORBES: Google's Trillion-Dollar Driverless Car -- Part 2: The Ripple Effects