How are you inserting the dates? If using Insert - Date and Time, remove the
Update Automatically check in the lower right part of the Date and Time
dialog box.
Note: with this option checked, Word inserts a date field. With this option
unchecked, Word inserts the actual text of the date.
The keyboard shortcut for Insert Date, and the icon on the header/footer
toolbar insert an automatically updating date field, {DATE}, so if either of
those were used in creating the doc, you get date changes.
To fix old docs, select the field, toggle field codes on the right-click
menu (or hit alt-F9), and change the DATE field to CREATEDATE.
If you just manually enter the date, I don't see any way Word could possibly
be changing it. Are you sure the dates aren't being converted into field
codes somehow? Press Alt+F9 to toggle field codes on/off. Does the date stay
a date, or does it change to reveal the field code?
If it IS a field code, you can convert it to hard text by selecting it and
pressing Ctrl+Shift+F9.
Thanks again. I looked now (and many times before) at the Insert - Date and
Time section and the box has never been checked, it has always been blank.
This is why its a mystery to me!