You can check for problems with the places.sqlite database file in the Firefox profile folder.

• http://kb.mozillazine.org/Bookmarks_history_and_toolbar_buttons_not_working_-_Firefox
• https://support.mozilla.org/kb/Bookmarks+not+saved#w_fix-the-bookmarks-file

• Places Maintenance: https://addons.mozilla.org/firefox/addon/places-maintenance/

It is best to disconnect Sync before trying to repair the places.sqlite file.

Thanks! I don't know if you're with Firefox or not but I find this solution to be odd. I've been in IT for 40+ years and have no problem dealing with a solution like this but does Mozilla really expect a normal end user to know what to do with a solution like this?