From: Livorno, Italy
You have received, and according to the descriptions you made, infected, too, by a virus called W32.Klez, or one of its variants.
When activated, it try to shut down any antivirus program installed on the victim's pc.
There's an alert on Warfare HQ site,too, about this; look:
Virus Alert by Scipio
Folks, keep your Virus Protection updated! I have received several infected mails in the last two days, all has as appendix a picture from warfarehq, usually a ladder image, that opens itself. Danger, this appendix is infected with the iframe.exploid or a w32.klez virus!!! An updated Norton can identify them.
However, I recomment to deactivate the preview of your email program and delete all suspicious mails.
Federico "Resisti" Doveri