hello dawnking -
I've seen the same issues w/98 and Win2k Pro machines. Same 1 minute refresh interval set. Seems to happen off and on with some machines. Also have noticed more so on Win2k box when writing a new email message (and see the mailbox behind with no new mail) Once you close or send the email . . . . Voilà! Generates the refresh.
I haven't tried this, but perhaps it's at the PO or GWIA setting. If I remember correctly, there's also a "refresh interval" in there somewhere. Maybe changing it to 2 minutes, then switching it back to 1 minute will kick something around to start working as it should. Since it occurs on all OS platforms, tends to lean towards the backend vs the client.
I'll dig around a little bit more within the settings. Maybe it's something we're overlooking, like threads, active send/receive connections, etc....
-- again, just reaching at possibilities.