Firefox should not log out or shut down Windows. Are you seeing any severe crashes, e.g., blue screen or black screen with a terminal-like font display?

PatrickConner said

When I used Internet Explorer I did not have to sign in to start 8.1 unless I had turned OFF my computer or I had put it to sleep. Thank you for your responses and I do Love Mozilla. Patrick

jscher2000 said

Firefox should not log out or shut down Windows. Are you seeing any severe crashes, e.g., blue screen or black screen with a terminal-like font display?

jscher2000 appreciate your help but nothing like that happens. Could it be because I do not store history. I browse in "private mode" and that could be the downside of that.

In PB mode Firefox uses a separate cookie jar and all cookies are session cookies that expire when the PB mode session is closed. That will prevent a website from remembering you because such a choice is stored in a cookie. As long as at least one Private Browsing mode window is open then you should keep the cookies.

Just to clarify, is Windows 8.1 shutting down by itself or is it locking itself? OR is Windows locking up and you have to restart it? I was assuming you meant it all happened while you were away, but I should have asked you in more detail what is happening.

To cor-el how do I keep "one PB window open"? yet still be in Private Browsing mode? Thank you. Can I keep the cookies and history from one site like my home page?Patrick

To jscher2000 my computer is running normally with no lock-ups or crashes. I do not have to restart just Log back in to use computer

Is Windows set to automatically lock after a period of inactivity? I'm not sure why that feature would work differently when you're using IE vs. Firefox. I though it was based on whether the mouse and keyboard were not being used.

When I look up that feature for Windows 8.1 I find some complicated explanations, such as: "show the lock screen after my pc is inactive for" setting missing on Microsoft's forums.