OK I'm not sure how to describe this so let me start at a basic point and
give some background.

I have Office 2003 running on my main laptop and my wife's desktop. I have a
LAN that connects our PCs as well as two other PCs. The golden rule is that
if some event is not on my calendar it may not happer or will be bumpted by
another event. If I make an entry in my calendar I "invite" my wife and then
with the click of a button she can add it to her calendar. She can also
create an entry on her calendar and invite me and with one click I've added
it to my calendar. So far all is good (BTW the invities are being sent via
email I DO NOT have an exchange server installed nor have I ever had one
installed0.

The other day I made several entries in my calendar and invited my wife to
each. As normal all appeared in her inbox but then we ran into a problem. A
couple of them appeared very normal and she could just click on the icon and
add them to her calendar. Two of the invites appeared as all text, there are
no icons in the invites. Thus she was not able to add them to her calendar
and deleted them. On my system I changed the time by one minute thus forcing
a resend of the two entries and again they appeared as all text messages in
her inbox.

Any idea what is going on and what I do to resolve the issue?

On both systems is
WinXP Pro
Office 2003
I've downloade all the latest updates from MS and they have been applied
without issue.