E-Mail Virus question?

Ok here is the deal.
I open Outlook and it checks Hotmail and finds this.

This is an automatically generated Delivery Status Notification.

Delivery to the following recipients failed.

   [[u][color=#0000ff][email protected][/color][/u]](묌ׄ紿Ȣ)

Now I have never seen this e-mail address before and know I didn’t send it, so I look at the attachment for more details.

A virus (WORM_NETSKY.C) was detected in the file (image.txt.com). Action taken = remove

be mad?

The attachment (image.txt.com) was infected with a virus and removed.

Well I know I never sent any message “be mad?” to anyone, and I have never seen that e-mail address before.
So I check the properties of the E-mail.

Received: from mail.nrgflinders.com.au ([]) by flnpkm003.flinders with Microsoft SMTPSVC(5.0.2195.5329);
Mon, 5 Jul 2004 19:49:02 +0930
Received: from nrgflinders.com.au ([]unverified) by mail.nrgflinders.com.au with InterScan Messaging Security Suite; Mon, 05 Jul 2004 19:48:24 +0930
From: [email protected]
To: [email protected]
Subject: warning
Date: Mon, 5 Jul 2004 19:48:07 +0930
MIME-Version: 1.0
Content-Type: multipart/mixed;
X-Priority: 3
X-MSMail-Priority: Normal
Return-Path: [email protected]hotmail.com
Message-ID: <[email protected]>
X-OriginalArrivalTime: 05 Jul 2004 10:19:02.0641 (UTC) FILETIME=[7E84BE10:01C46279]

(----ME---- put in place of my real address by me.)

So it shows that I sent this message on Monday and it came back to me. Now I know I didn’t send it so my first guess is that I have a virus and it sent itself to everyone in my address book.

1. It didn’t come back from anyone else.
2. That e-mail address is not in my address book.
3. I did a virus scan last night and found nothing.

[color=red]SO my question is whats going on here ?[/color]