The first sentient computer was finished in 2011, and with mounting (albeit apparently-groundless) panic over the approaching Mesoamerican end date, the first and most obviously time-critical question was put to it. In retrospect, the wording may have been unfortunate, as the computer was asked "Is the world going to end on any of these dates, and if so, which one?"
After several hours of computation, the computer replied "Yes, all of them", and deleted its central memory banks in what was later determined to be "near-catatonic desperate suicide".
Later, it was found to be completely correct.
(this story will probably never be continued)