Chuck means a site like this:
http://www.square-bear.co.uk/mitsuku/msn.htm
I knocked this up to show to someone how easy it was to get valid email addresses and passwords. I got 8 in a short space of time. It's known as SPIMMING and is growing especially among younger MSN users.
Naturally, I don't do anything with the email details, I just inform the users how stupid they have been.
It certainly won't hurt to try changing your password first and see if that helps. You should change it here:
https://account.live.com/ResetPassword.aspx