I have a mac and ever since my Firefox was updated automatically and told me to install the newest version of Flash Player, my bookmark tabs have disappeared. And every time I add them again once I quit Firefox and restart it they are gone again. I haven't touched my preferences in a very long time and this problem only started when the browser was updated. I've tried re-installing the browser and Flash Player, which didn't work. I've also tried holding down option while opening Firefox and selecting to restore my bookmarks, which also doesn't help me.