Suspected infected with email worm

Hi. I suspect that I am infected by some kinda email worm. What happanes is this: A few times per day I get emails saying my email that I sent (which I havent sent) has not been delivered due to various reasons. This is one example of many:

"This is the mail system at host amatex.ro.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

The mail system

<k1029slick@netzero.com>: delivery temporarily suspended: host
mx.vgs.untd.com[64.136.52.37] refused to talk to me: 550 Access
denied...3224d0906005942434f059f0e9717149d92d54a9b5b0e109c1402121402d25113025edf5004d4df5a94ddd343d95953d8d317909312424e1f9a1...



Reporting-MTA: dns; amatex.ro
X-Postfix-Queue-ID: 04013ED240
X-Postfix-Sender: rfc822; lazboy@bredband.net
Arrival-Date: Mon, 5 Oct 2009 08:52:24 +0300 (EEST)

Final-Recipient: rfc822; k1029slick@netzero.com
Original-Recipient: rfc822;k1029slick@netzero.com
Action: failed
Status: 4.0.0
Diagnostic-Code: X-Postfix; delivery temporarily suspended: host
mx.vgs.untd.com[64.136.52.37] refused to talk to me: 550 Access
denied...3224d0906005942434f059f0e9717149d92d54a9b5b0e109c1402121402d25113025edf5004d4df5a94ddd343d95953d8d317909312424e1f9a1...""


And the emails I "supposedely" sent has an attachment named "Part 1.2". I use Avira as antivir and Malwarebyes. I use the built in firewall in Windows 7 x64 + Windows Vista/7 Firewall Control. I have scanned my computer with Avira, Malwarebytes, Hitman Pro, Trend Micro House Call and none of them report anything.

Here is my hijackthis log:


~ HJT Log Removed as per Policy ~

Does anyone have any idea whats going on? What can I do to clean my system? I would greatly appreciate any advice I can get. I know a reformat/reinstall win7 would do the trick but If I could clean my system that would be prefered if possible.

Thanx in advance / Matt