Turned out to be because it was generating a date by calling a general purpose astronomical routine, then parsing the date out of that. The astronomical routine among other things included the phase of the moon, and during some phases you would overflow the buffer that was passed in.
Another classic was a tech support call from the 1990s where the person's computer rebooted every time they flushed the toilet. Turns out that the person was at the end of the electrical line..and on a septic system. Flush the toilet, the septic system came online, causing a power dip, and that was enough to reboot the computer. A UPS fixed that.
They thought it might be static electricity, or some mechanical problem, or "problem exists between keyboard and chair", but finally they noticed something else was amiss...
It turns out some joker had re-arranged the 1234567890 keys to be 0123456789, so when the user was standing up, they looked down at the keyboard and typed their password (which contained a digit, of course) by looking at the keys. But when they were sitting down, they touch typed without looking at the keys, and got their password correct!
So, eventually, just decided to stay at lab for the night. At 5AM the air conditioning came on (it was shut for the night). The ISDN circuit got stuck.
It was electromagnetic interference from the massive AC unit fan which was not too far above our lab table. Improving the grounding of the ISDN chip helped.
Want to convert acreage into MWh of annual solar electric potential, or figure out the oil equivalent energy in a nation's poop? Units can do that. And much more.
Two [BeOS] test engineers were in a crunch. The floppy drive they were currently
testing would work all day while they ran a variety of stress tests, but the
exact same tests would run for only eight hours at night.
After a few days of double-checking the hardware, the testing procedure, and the
recording devices, they decided to stay the night and watch what happened. For
eight hours they stared at the floppy drive and drank espresso. The long dark
night slowly turned into day and the sun shone in the window. The angled sunlight
triggered the write-protection mechanism, which caused a write failure. A new
casing was designed and the problem was solved.
Do you have a name for this program? It sounds a lot like an urban legend - when would you ever find it easier to parse a date out of an astronomical program than to use actual date handing capabilities from the system or a library?
The one that I described I first remember hearing about in undergrad. I heard it from an astronomy student. I guess that makes it an urban legend, but a highly believable one. In my experience inexperienced programmers are very good at unexpectedly repurposing whatever they happen to know for new purposes. And in an astronomy department it is easy to find inexperienced programmers with astronomical routines at hand.