This is a strange one - and more of a nuisance, but still.

I have two identically set-up machines. Or so I thought. Because I have a
problem on one I don't have on the other, yet I can't find what could
possibly be the difference.

I am running XP SP2.

I am running OE 6 (actually, 6.00.2900.2180 (xpsp_sp2_rtm.040803-2158)).

I have three accounts on my OE. One is a POP3, the other two are IMAP.

One of the IMAP accounts downloads new messages automatically, the other
just downloads new headers, and I decide when to download the message.

I frequently read my messages directly in Preview Mode.

In other words, I frequently have "New" messages in my inbox.

On the ONE machine - and on every machine I've ever used in "Real" Outlook -
when I mark a message as READ, the little envelope goes away...

AND STAYS AWAY UNTIL I ACTUALLY RECEIVE A NEW MESSAGE.

Now, here's the nuisance (long windup for small payoff!):

On the one machine, if I have ANY Unread messages, the little envelope in my
Taskbar pops back up.

I presume what's happening is, OE polls the inboxes, sees unread messages,
and then re-alerts me. Of course, I already know the message is there, but I
flip over, because I think maybe I have NEW New message.

On the other machine, the little envelope only pops up when a new message -
a "real" new message - hits my inbox.

So...

Is there a switch somewhere I'm missing?

Thanks