Hi Ellen, You could also try deleting bookmarks this way : # Click the 3-bar '''menu icon ''' # On the right panel click '''Library''' # Click '''Bookmarks ''' # Right-click to select the one you want to delete. '''Or''' # Click the 3-bar '''menu icon ''' # On the right panel click '''Library''' # Click '''Bookmarks ''' # Click '''Bookmarking Tools''' # Click '''View Bookmarks Sidebar''' # Select the individual folders on the side panel and right click the desired bookmark you would like to delete. You could try booting up in '''Safe Mode''' with Firefox to see if the issues go away : # Click the menu '3-bar'. # Click Help (towards the bottom). # Click Restart with Add-ons Disabled.... # Click Restart. # When given the choice, click Start in Safe Mode. You could try to clear your cache in your web browser. To do this : 1 Click the hamburger 3-bar menu in the top right of your web browser 2 On the left-side panel click Privacy & Security 3 Under Cookies and Site Data '''Warning! ''' Clearing all cookies and site data stored by Nightly may sign you out of websites and remove offline web content. Clearing cache data will not affect your logins.''''' 4 Click Clear Data... 5 Check mark Cookies and Site Data 6 Check mark Cached Web Content 7 Click Clear Hope this helps!

This is a duplicate question .... See : https://support.mozilla.org/en-US/questions/1268614