microsoft.public.word.vba.general

I've got an old asp.net app that populates some custom fields on a word
document it generates. These fields are embeded in the text so that the
values are inserted into the letter (things like addressee_name etc) and can
be seen when the document is opened. To do some maintenance we have moved the
app onto a new (virtual) development server but now the text doesn't get
updated immediately when the properties are written - yet this does happen on
our production system. If you Select All and Update Fields (Ctl-A, F9) the
values appear so the properties are being written OK. Does anyone know what I
am missing?
(The original developer has left the company, hence my confusion).
R