I used to be a firefox fanbuio, i even used waterfox which is their (at that time) 64 bit version of the firefox. Once fine day I installed new OS, and my beloved FF and bang .. I lost all bookmarks forever. I emailed them, they gave me generic troubleshooting steps which I had already tried. Now I don't use FF at all. I have chrome as my default everywhere (home/office) and have Opera as secondary.