"Simple. I got very bored and depressed, so I went and plugged myself in to its external computer feed. I talked to the computer at great length and explained my view of the Universe to it," said Marvin.
"And what happened?" pressed Ford.
"It committed suicide," said Marvin and stalked off back to the Heart of Gold.

A computer chatted to itself in alarm as it noticed an airlock open and close itself for no apparent reason.

This was because Reason was in fact out to lunch.
A hole had just appeared in the Galaxy. It was exactly a nothingth of a second long, a nothingth of an inch wide, and quite a lot of million light years from end to end.
As it closed up lots of paper hats and party balloons fell out of it and drifted off through the universe. A team of seven three- foot-high market analysts fell out of it and died, partly of asphyxication, partly of surprise.

Two hundred and thirty-nine thousand lightly fried eggs fell out of it too, materializing in a large woobly heap on the famine- struck land of Poghril in the Pansel system.

The whole Poghril tribe had died out from famine except for one last man who died of cholesterol poisoning some weeks later.