This week has seen another example of the chaos that can ensue when complex computer systems fail. On Tech Tent we try to draw some lessons from the British Airways IT fiasco.
We also discuss bullying in online games and hear what the criminal underworld is saying about the WannaCry ransomware attack.
Lessons from an IT disaster
Last weekend's catastrophic failure in BA's computer system threw the travel plans of 75,000 passengers into chaos. What went wrong has become a little clearer - it appears the power somehow went off at a Heathrow data centre and when it was switched back on a power surge somehow took out the whole system.
Airline bosses insist that this means the whole incident was a power failure not an IT failure - but experts point out that power management is an essential element of any well-planned IT system.
Bert Craven of the consultancy T2RL, who has designed systems for major airlines, tells us the real question is whether the airline had what he calls geo-redundancy.
"This is a duplicate mirrored system in a data centre at a distance. Clearly either that was not the case or there was also a problem with the geo-redundant system at the same time - a perfect storm."
He reckons every airline IT executive will have been hauled out of their bed last weekend to be asked: "Could this happen to us?"
Passengers may be tempted to ask whether it would be simpler to abandon the computers and return to paper. Mr Craven tells us that until a few years ago, airports were in the habit of printing out passenger manifests and other documents at the beginning of the day just in case things went wrong.
These days however there is just too much real-time data involved in running complex airline operations for that to be feasible. Only computers can make modern air travel work, and when they fail it is like throwing sand into the machine.
We are all sadly familiar with the problem of abuse and bullying on social networks. But this week the anti-bullying charity Ditch The Label published research showing the extent of the problem in online video games.
Its survey, carried out through the online game Habbo Hotel, showed more than half of young gamers reported that they had been subjected to hate speech while playing online. Bailey Mitchell, 16, told me he'd first experienced abuse when he was 10.
And it was more than just banter - he was told to kill himself after scoring a goal in Fifa. Nowadays, he says, he can shrug it off, but when he was younger he'd come home from being bullied at school expecting to escape into a game, only to face abuse there too.
The games industry was a bit sniffy about the charity's report, unconvinced that Habbo Hotel was the right place to get an overview of the gaming scene.
Jo Twist of the British games body Ukie tells us that the industry is already acting responsibly, using everything from AI and semantic analysis to human moderators to detect abuse.
"Players are our lifeblood," she says. "We use all sorts of tools to make sure they have a safe experience."
But she says it's also up to players and parents to take responsibility. "There are games that are suitable for everybody - and some games are only suitable for 18-plus audiences."
WannaCry and the Underworld
It's still not clear who was behind last month's WannaCry ransomware attack, which affected organisations around the world, including hospitals here in the UK. But whoever it was, it seems the criminal underworld was not happy about it.
Andrei Barysevich is a cyber-security researcher at the Recorded Future threat intelligence company, who works as a consultant to the FBI and spends a lot of time monitoring the dark web.
He tells us that criminal hackers were not at all impressed by the high-profile nature of the attack - and were particularly angry about hospitals and police forces being attacked. Not because they were squeamish, you understand, but because governments and law enforcement agencies are on the warpath - and that has put criminal hackers in the spotlight.
It seems there was even a meeting of elders of the criminal underground, at which they all declared that this attack was nothing to do with them. It seems that WannaCry was probably hatched by a relatively amateur group of hackers who may have been surprised by just how much mayhem they unleashed.
It is as if a nuclear weapon fell into the hands of a group of teenage pranksters who thought it was just a firecracker - not an entirely reassuring thought.