Some web sites have a 'timer' for user inactivity. Then logs the user out. This is a site security measure. Not Firefox. Contact your e-mail provider and ask questions. BTW, at the time, were you on any other web pages? If so, the alert could have come from that.

Thanks Fred McD.

I was on another web page before I logged into my email. Will check my web history if or when it happens again and find out what site I was on before I logged into email. Appreciate your prompt response. Will follow up on your recommendation.

If you did not log out of that site, that could be the issue.

Hi Fred McD:

Thanks again for your help. You were right. It was a web site "timer".

Today I got a banner headline that said:

Xfinity (by Comcast.net) has logged me out due to inactivity. If I wanted to resume, to click here. When I "clicked here", my email account came up. This is the first time I have seen this banner. Must be something new in their system. Mystery solved.

Good to hear. ALWAYS remember to log out of high security web sites, like those that your personal information, address, credit info . . . . . . . . Forum sites, like this one, you don't need to worry about since it has no private information. Safe Surfing.