Recently I was training an advanced InDesign course, and one of trainees had come across a problem and asked me for advice. The problem she had come across was, whenever she imported Excel documents into InDesign, the dates switched formats.
What was happening was that the date was formatted within Excel as an english date format (say 1/12/11) but after importing into InDesign it swapped into an American date format (12/1/11). And she could not figure out why.
After a few minutes of investigation I finally figured out why. Here is a screenshot of a simple Excel table. Just a column of dates, formatted (you might think) in the English date format.