As computers become more capable, it's humans who are not always keeping up. And although researchers keep making progress towards artificial intelligence, nobody has solved the problem of natural stupidity. When human meets computer, the results can be amusing - or alarming.
Examples abound. In a recent test, US Homeland Security scattered USB thumb drives in the car parks of government buildings. Of the people who picked them up, 60 per cent plugged them into office computers, despite regular warnings that this is a classic way to infect an entire network. So much for security.
Carelessness, stupidity or ignorance can also make a computer a dangerous weapon. In May of 2010, a US stock market "flash crash" of more than 1,000 points in 30 minutes was traced to computer programs that triggered selling when they detected certain market behaviour. The problem wasn't the program; it was blind trust in a series of zeroes and ones.
Or how about when New York City police raided the home of a law-abiding elderly couple 50 times over eight years? Their address had been put into a police computer at random during a system test. The list goes on.
Life without computers is no longer imaginable, but life with them can be complicated by human, not machine, failures. "Against stupidity," wrote the German poet Schiller, "the gods themselves contend in vain."