From 1998 through the end of 1999 I was the lead engineer for testing batch scheduling, using CA's Autosys product, at a now-defunct and quite infamous large investment firm. I spent days and weeks and months running and rerunning, testing and rebuilding and reloading our batch processes in anticipation of the change of the millenium and the end of our civilization.
So when the clocks started ticking over from 1999 to 2000, beginning in the Pacific Ocean and then through Australia and Asia, Europe and Africa, and finally the Americas, nothing happened. It was just another batch cycle, with no disruptions.
The only disaster was that no one invited me to the party where they celebrated the success of this project.