Outlook.com hacked/sending spam help required please

I'm hoping someone can give me some help with my outlook.com/hotmail email account.  

My account appears to have been hacked to send out spam to my contacts, and also some addresses that I do not know.  I found out about this on 10/11/13 when my friend text me to say she had just got a suspicious looking email from my address, I logged in and there were no items in my sent box, however my inbox had about 6 messages from postmaster saying undelivered, I could see from these bounced ones that they had been also sent to my contacts and several others.   The email appeared to have an attachment re.eml (obviously didn't open it, and advised my friends not to if they got it either), and also contain a link, something about 'recommend adobe and deonoffdelights' or somesuch.  All my other emails in my inbox and folders appear untouched, nothing deleted either.

After this I changed my password, have run malwarebytes, spybot search and destroy, windows defender, microsoft malicious software removal tool and have always had avast antivirus running, none of these program scans picked up anything infected, so I assumed that was the end of it.  I have not used any public computers to access my emails either, only my home laptop where there is only me there anyway.

However yesterday about 11.15GMT I got another mail from postmaster in my inbox as a delivery failed notification to an address I don't know of, again with the same re.eml attached and the same message that I recommend the link in the email.  I changed my password again, but have had the same email again.  (though again looks like just one attempted to be sent).

Could anyone please advise on what my be happening here, as changing my password and security details does not seem to be working.  Is my account/email address infected somehow? Or are these emails i'm getting in my inbox as delivery failed notifications from postmaster just a delayed reaction from the original hack on 10/11/13? I don't really want to use my email at the moment if its still compromised.

Any help would be greatly appreciated.

Many thanks,

Matt