all still human problems. it's just a matter of what human get yelled at.
...if they have a manufacturing fault,
(human) design error
or overheat,
(human) design error
or receive sharp knocks or vibration,
(human)design/enviromental issue
or experience power fluctuations,
(human)design/enviromental issue
or are short circuited by moisture/insects/hair/other foreign matter,
(human)design/enviromental issue
or are struck by cosmic rays,
(human)design/enviromental issue (yes kiddies, even this can be protected against, It's just useually not worth the money to do it)
or any of hundreds of unpredictable phenomenon.
We design a machine to operate under specified tolerances. If it fails while within the tolerances that's a human design problem (the machine doesn't operate in spec). If it fails while operating outside the operating paramiters, that is an enviromental design issue (you monkeys need to stop peeing on the kit), which is again a 'human' (i use that in the loosest sence of the word) problem.