I am wondering why it is happening, also. The data source is a Visual Foxpro6 table. I have a table with 140 fields (20 sets of 7) and a Word form set up to merge these fields. It may have only two sets of fields filled in, but I get 12/30/1899 displayed in the other 18. I opened the table (in VFP) and verified that these fields are blank but it still displays the odd date.
By the way, I have also posted this on EE and will give you the points there if you respond there. It was down for an hour when I was trying to find a reason for this problem.