I opened Firefox this morning. Received dialog box asking me to check box to retrieve info. I checked Firefox (not Safari, etc.). Opened Firefox...nada. Then got request to upgrade so I did, thinking maybe this was part of the upgrade. downloaded upgrade and tried to drag & drop into my Applications directory. Told was "newer" version there already. But checking showed me that the version in my Apps directory was the old version. So I used "App Cleaner" to get rid of it (but kept the plist). Then I moved the new Firefox into Apps and opened it. Still nothing. I do have Firefox menu across the top but "View/Sidebar/Bookmarks" gets me nothing but the default locations.