Why do my shared calendars disappear in Outlook?

We also are running '03 and '07 mixed environment on exchange 2003
with disappearing calendars. Anyone find a fix besides:

Periodically, the list of shared Calendars will disappear and these
Calendars
will need to be reopened to rebuild the list.
There are significant differences in the architecture of Microsoft
Outlook
2003 and 2007, and in the case of People's Calendars, Microsoft
Outlook 2007
stores the shared list in the user's mailbox on the Exchange Server
instead
of locally on the client workstation thereby providing the list to
multiple
clients accessing the mailbox. The downside to this approach is the
potential
for network connectivity issues which might cause the data to be
written
incorrectly or corrupted and not delivered properly to the client.
Microsoft has now stated as of 6/7/07 that there is a bug regarding
shared
calendars disappearing when users are in online mode. This fix is
expected
to be rolled into Office 2007 SP1. In the meantime we recommend that
you run
Outlook 2007 in cached Exchange mode if you are having this problem.