Contacts anniversay date loses a day

I can't tell if this is a Messenger problem, Windows Live problem, or
Outlook Connector problem.

Here's what's going on: Anniversary dates in Messenger contact properties
get out of sync with the anniversay dates that I see in Outlook Hotmail
contacts by one day. The strangest thing is that I can't even see how
they're connected. I say this because when I look at all editable
properties for a contact using the Windows Live web interface there isn't
an anniversary item.

How can I troubleshoot this?

--
Mike H