In Office XP Professional, using Excel 2002 spreadsheet as data source for
Word 2002 letter merge worked many times before and now doesn't. The zip code
field changes from 5-9 digits to zero in about 1/3 of the letters. Remaining
2/3 of letters merge correctly. The zip codes that change are not just those
with a zero at the beginning of the 5-9 digits. Some of the 9 digits zip
codes change to zero now but didn't previously.

If I use a previously saved version of the spreadsheet, the merge prints out
correctly. However, if I make changes to the spreadsheet, some of the zip
code fields print as zero again. I have been using a version of the letter
and spreadsheet for over a year without any problems, until now.