Those messages are from someone who is infected, but they have just spoofed your email address as the return address when the virus tries to infect others by email.
Just run a full system scan using your antivirus to make sure that there is nothing to worry about. If the scan result is clean, just ignore and delete those e-mails.
You can use a program like Mailwasher from http:/www.mailwasher.net or Magic Mail Monitor http://mmm3.sourceforge.net/ or eprompter http://www.eprompter.com to preview your emails from the server. Delete the unwanted emails from the server before launching Outlook Express to download the "good emails".
I have used Outlook Express for many years to my access email accounts for both Hotmail and my ISP provider without incident until recently. I am now receiving daily attacks of viruses to all my email accounts. What has really got be worried is that I am receiving undelivered message emails from other servers saying a virus or email i sent to them was undeliverable. I do not know who these people are, they are not in my address book and I certainly did not send them anything. Is this some virus that my Nortons Anti-Virus has not detected? How can someone take over someone elses email domain so easily and use my name to spam other users and infect other networks? Also I occasionally receive these viruses from people I know, but some of them are not in my address book :S Anyone have any idea how to stop these attacks?