Milan, December 12 - Delays and cancellations of trains in Milan and Lombardy continued to harry some commuters Wednesday morning after malfunctioning train-tracking software wrecked widespread commuting chaos Tuesday evening. Tens of thousands of passengers found themselves stranded on Tuesday when a new computer system, introduced on Sunday, went haywire. The system, which manages rail worker shifts, assignments and the configuration of trains, began to show trouble on Monday. By late Tuesday, numerous trains were left without necessary personnel; and trains were configured without considering timing and destination. Trains were running far better by Wednesday morning, but delays and cancellations still affected lines arriving to a main downtown Milan station, Cadorna. There were 20 cancelled trains out of a total of 250 during the 7-9am rush hour, the rail company Trenord announced on Wednesday. Trenord publicly apologized to its passengers on Tuesday.