Mysteriously, FF v48.0.1 now launches at start-up. Mac 10.7.5. Just started doing this 3 weeks ago. In system pref, it is not checked as log-in item. Am stuck running on older OS due to vital software that has not been upgraded (replacement software search in progress). Have searched preferences - can find no setting. Have Googled - nothing pertinent, or applied to older versions, not this one. I guess I can deal with it but it's so annoying. My machine is running slow enough as it is, and this slows start-up down.