It became apparent in the late 1990s that many programmers had not implemented the rule for calculating leap years correctly - 2000 was a leap year despite being a multiple of 100.
In the popular papers this was considered a crisis that would be the end of life as we know it; come New Years Day 2000 everything with a computer in it would stop working.
Being a programmer I imagined this would be easy money coming my way plus the chance to be useful. It turned out the government relaxed the rules and allowed lots of programmers from the rest of the world to come here and work.
I was reduced to trying to find Y2K bugs to fix for free. The patch below is for MasterFile 3, a Beebug database product.
Turned the fateful hour we watched Tony Blair joining hands with the Queen and singing Auld Lang Syne in the Millennium dome - and nothing happened.