Contact MSN tech support to have them check on the issue. Also, inform your friends and associates so they won't click to open any links coming from you. This is because the most likely scenario here is that your account may have been hacked.
3. What to do when my MSN account was blocked?
Your MSN account may get blocked because someone used the account to send many junk messages. To get your account unblocked, MSN technical support will guide you through answering some questions for verification that it is truly you that owns the account. You can now change your password to make it inaccessible to others.