It could be either.  (Word's behaviour in this area changed radically
between Word 2000 and Word 2002/3 and to an extent between 2002/2003, and as
a result of security updates made in SPs etc.), so I would not expect you to
be able to copy a Word 2003 template to Word 2000 and use it successfully
without change, or vice versa, but once you have got a particular template
to work with Word 2000 I would expect it to carry on working with Word 2000,
and the same for a template you had got working with Word 2003. If something
has stopped working, it is probably because of a recent update.

Another possibility is that a change has been made to your data source
database configuration (what type of database are you using?), e.g. to
restrict the number of simultaneous users, or to change a timeout of some
kind.

If you are making connections programmatically, you must take account of the
following KB article:

"Opening This Will Run the Following SQL Command" Message When You Open a
Word Document - 825765 at:

http://support.microsoft.com?kbid=825765

but it doesn't sound like that is the issue in your case.

Peter Jamieson