See "Formatting Word fields with switches" on fellow MVP Graham Mayor's
website at

http://www.gmayor.com/formatting_word_fields.htm

If that doesn't work, I think you will have to look at the Excel
spreadsheets to try and detect differences between the formatting of the
cells on the one that works and the one that doesn't.
--
Hope this helps.

Please reply to the newsgroup unless you wish to avail yourself of my
services on a paid consulting basis.

Doug Robbins - Word MVP

"enolalum" wrote in message
...
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.