[jujuwillis]

Completely understand your situation - and of course "it wasn't them" either.
I am assuming others are picking up the documents from the server. Does
each user have their own details filled in in user information? Tools,
Options, User Information? If they are the user will likely to be set to
"their name".
If that is the case, when you open a saved document, File, New and have your
view set to properties view, then it shows you , Title, Author, keywords,
comments, template and ....... Saved By. It also shows other things like
when the document was created and any other custom properties up might have
set in your document.
So, even if no one else has their "User Information" set, at least if you
do, if someone changes your document or "Save's As" the document properties
will reflect this.
Also, if you fill in the "initials" part as well then you can insert your
inititals as a field in your document/template Insert, Field, User
information and if someone else saves - their initials. Hope it helps.