Couple of different things could be the trouble.
1. When you say that the document gets redated, do you mean a date inserted in the document? Or the file itself?
If it's a date field in the document, you can use the 'Insert.....Date/Time' menu option to have Word insert the date field for you. If you want Word to automatically update the field when you open the file make sure the 'Update automatically' option is ticked.
Obviously the don't tick if you don't want it to update the entry. This is the equivalent of you typing the date in manually as normal text entry.
2. If it's the *file* date that gets changed, are you saving the recently opened file? Or perhaps you have Autosave enable.
This would over-write the old file & its file date stamp with the just saved version.
Somewhere under the 'Tools.....Options' menu is the facility to disable Autosave. Hopefully this will do the trick.
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OOPS! Misread the part about it happening in 'My documents'. Somehow I thought the original post was a Word problem. <wanders off mumbling some blather or other...>
[This message has been edited by Tinstaafl (edited 06 January 2000).]