The computer-speak term for this situation is "account compromise," use this term when communicating with the Live support folks.
Your Hotmail account is now owned by the folks at Windows Live, which is why you will find the Windows Live help topic for this under Account Compromise - Unauthorized Account Access.
Go now to http://account.live.com and add Password Reset Information to your account and encourage your friends and family to do the same.
If you are the hacked/hijacked account owner:
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In the section "Can you improve this article?" it says "Positively! Click Sign In to add the tip, solution, correction or comment that will help other users." It would be helpful it it said something like "go to the Leave a Comment section below after you Sign In".
In the "Here are the steps you should take" section #2 is not fully exposed. I only see line 1 and the top part of the second line. (are there additional lines?)
suggestion for rewrite of Reactive #2: Run a malware scan on all computers you use to access the account. The free Malicious Software Removal Tool (click to download) will do this for you.
If there is something like a keylogger installed that will steal your passwords the bad guys will get your changed password too.
suggestion for #2 "If there is something like a keylogger installed that will steal your passwords the bad guys will get your changed password too. " Suggest the user change their password on a different computer.
my account recently got hacked, and this helped. it kept on sending emails from a company, i never found out why.