Exchange 97/ outlook 2000 question for mail gurus :)

Slight problem, noticed today on our helpdesk that 2 emails (they seem completely normal) show up on exchange 97 but not if you're viewing the same inbox on outlook.

Basically we're looking at upgrading all the computers to outlook 2000 and I'm a little worried this could mean them missing some emails. Currently they're all using outlook 2000 sp1 so perhaps the service pack will help but does anyone know what could cause this odd behaviour? or has anyone come over it in the past.

Additional:

Oddly I think it's to do with the messages being marked as "private" and going to a communal mailbox rather than directly to those reading the messages. Just seems odd that it'd be visible in exchange and not in outlook :)

Sorted, they didn't have delegate rights to view private messages in the communal mailbox. Oddly only needs this if your using outlook.