The Riddle of the Universe and Its Solution Wikipedia
The Riddle of the Universe and Its Solution is a short story written by Christopher Cherniak appearing in the 1981 book The Mind's I. It describes a research project in computer science which includes content that produces catatonia in anyone who views it. The material is harmful only if comprehended by its victim—in some cases there is an incubation period before an exposed subject reaches the fatal conclusion. Often, the last thing said by such individuals before slipping irrevocably into a coma is "Aha!"
Only after the lethal files tragically affect a team which fetches them remotely—hoping to avoid a presumed biological disease—is the true danger realised. Efforts to use apes to discover which part of the files has this effect fail: so the effect is limited to humans.