Help! My Windows Live Mail - Email Has Been Hijacked!

My Windows Live email client has apparently been hijacked because it's sending out commercial messages from my email address. I've tried 3 anti virus scans:
Malwarebytes Free Virus Scanner and TrendMicro http://us.trendmicro.com/us/home/
and Microsoft's Windows Malicious Software Remover Tool (http://www.microsoft.com/downloads/details.aspx?FamilyID=ad724ae0-e72d-4f54-9ab3-75b8eb148356&displaylang=en) -- but none helped.

I also changed my password and secret question/answer, but that apparently did not help either.

I don't want to change emails if I don't absolutely have to, so please give me some suggestions. I desperately need help.

And by the way, even if I do get a new email, won't the old, virused email client still continue to send out these commercial emails in my name? Is there a way to permanently shut down/terminate/disable my old Windows Live Email?

 

First you need to check whether the spam emails really are being sent from your account - 'view headers' will give you enough details to ascertain where they originate.

You can paste the headers here but *** out any real email addresses first.

If they do originate from your account or PC, follow up with Halo's advice.