hello, please try to reset firefox and see if this can address the issue...

did the reset when logged as "guest"; it does not correct the problem;

Problems with bookmarks and history not working properly can be caused by a corrupted places.sqlite database file.

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

Did you check the values of the browser.urlbar.* prefs on the about:config page? browser.urlbar.autocomplete.enabled browser.urlbar.autoFill browser.urlbar.maxRichResults

Your System Details List shows two general.useragent.extra.btrs prefs that you can reset via the right-click context menu on the about:config page

I tried the "places maintenance" add-on, but it seemed to be hanging. The values of browser.urlbar* were correct Finally i deleted the "places.sqlite" file and that seems to solve the problem. Thank you