My leap year tale
Exactly 40 years ago, I was working for an IT company which supplied software for pathology labs in hospitals - basically databases of results of blood tests, urine tests, and other unmentionable things.
Quality wasn't very good, but, having been there for only a year, I was trying to improve it.
Feb 29 rolled around, so I sat back and waited for the phone to ring. Nothing. No complaints. Had we got through it? No. The next day, March 1st, the complaints came in.
At some time in the previous four years, before I joined, someone had added a "delta check" facility to the software. This checked a patient's latest results against their previous results, and raised an alarm if they were changing too quickly.
Whoever programmed the delta check had forgotten about February having 29 days every four years. So when it compared new results against older ones, it calculated the time difference to be 24 hours less than it really was... and all hell broke loose as a large number of patients were flagged as needing attention.
Only good thing about it was that eight years later, New Scientist magazine published an article which I had written about it. I had realised that in 1992 they would have an issue actually dated 29th February, so I submitted an article recounting the above leap year woes, and then looking forward to 01 January 2000 - one of the early mentions of what became known as the Millennium Bug.
The next week they published a letter by one Arthur C Clarke, saying "interesting article, but I described this problem, and a solution, in my book......". I later saw several very similar letters from him, on other topics, so he must have had a standard template that he just added the appropriate details to before firing it off to the magazine.