Windows live messenger hacked - sending links and messages

Hi!
First I'd like to apologize if this thread is in wrong section (not sure about that)

My windows live messenger got somehow hacked or something, and now it automatically log in from another location and same time changes my msn picture, name, and status message, after that it starts to speak to everybody in my msn list like a "horny girl" and it sends links. My other windows live account got also hacked (I had logged in with it on this computer).
I'm not sure what to do, I've ran my F-secure scan and it found 1 virus that i deleted, after that i ran Spybot S&D and it deleted every bad program it found and after that i changed my accounts passwords but it didn't work. What should i do and how hacker still gets my password even i changed it?
PS. sorry for my english