E-mail sender changed (probalby Virus)

Dear Group,

I have a box, which runs Windows XP SP2 (like 1 year old), with
installed MS Outlook 2003.
The problem:

1. I compose an e-mail to john.smiths@localhost as John Mark
(john.mark@anotherhost) in my MSOutlook, I send it via SMTP_1 server,
with authorization, etc.
2. I log into account john.smiths@localhost via www, and I see that I
received an email with changed name (not john smiths) but with
unchanged e-mail address, and with changed subject and e-mail body.

Sample e-mail message:

Delivered-To: john.smiths@xxxxxxxxx
Received: by with SMTP id z14cs15991waa;
Thu, 27 Sep 2007 04:14:10 -0700 (PDT)
Received: by with SMTP id w13mr3473656ugi.1190891648852;
Thu, 27 Sep 2007 04:14:08 -0700 (PDT)
Return-Path: <john.smiths@localhost>
Received: from gazik.biz (xdsl-538.wroclaw.dialog.net.pl
by mx.google.com with ESMTP id e23si5548591ugd.
Thu, 27 Sep 2007 04:14:08 -0700 (PDT)
Received: from static-87-105-185-225.ssp.dialog.net.pl
([] helo=[])
by localhost with esmtpa (Exim 4.66)
(envelope-from <john.smiths@localhost>)
id 1IarJj-0005n2-S2
for john.smiths@xxxxxxxxx; Thu, 27 Sep 2007 13:14:05 +0200
Received: from [] by ; Thu, 27 Sep 2007 12:03:26 +0100
From: "Emilia Ibarra" <john.smiths@localhost>
To: <john.smiths@xxxxxxxxx>
Subject: -(+]) -+*:! ]*-[)+*-.[]:.+*-.(!
Date: Thu, 27 Sep 2007 12:03:26 +0100
MIME-Version: 1.0
Content-Type: text/plain;
Message-Id: <E1IarJj-0005n2-S2@localhost>
X_Spam_pemzNet: Spam score equals: -0.2

As you can see, the body message is empty, where I've send a message
which contained 'This is a text message' string in body area.
The 'Emilia Ibarra' is unknown sender, and naturally unwanted.
On the other hand, I receive e-mails perfectly, with exact names and e-

The problem is, that I used some anti-virus scanned, which gave me
none results.

Where shall I look for solution?

Thank you very much for help & if I should change my group, tell me
where I should look for help!

All the best,
Przemek M. Zawada