Macbook pro keeps returning to login window No matter what settings I apply within System Preferences, after a time of inactivity the login screen pops up. I'm attempting to backup to an external hard drive and create a time machine backup, but both stop once the login screen appears.

What setting am I missing that will prevent this from happening?
Are you sure it's the full login screen or is it just asking for your password?

If so, you can turn off "Require Password ______ after sleep or screen saver begins" in the "Security and Privacy" system preference.