Hi Marinfischer, Are you talking about messenger built into mail? If so, that is something that is built into Yahoo mail. You should consult their documentation for information. If you are talking about the Messenger features built into Yahoo toolbar, you should remove the Yahoo toolbar by going to ''Tools > Addons''. If you are talking about the actual Messenger app, you might have set the app to start when you start your computer. I would disable the open at startup feature. Hopefully this helps!