Hi gujatheljuta,

Two questions:

• What happens when you type in the address bar?

Is the drop-down completely empty or does it still show your bookmarked/tagged websites (if any)?

• Did you clean your browsing history recently, in Firefox or using a tool like CCleaner?

"What happens when you type in the address bar? " When I type letter Y nothing happens, when I type M or S a single drop-down item appears with "Visit <most visited URL>" link. When I type any other letter drop-down list appears as expected, with dozen most visited pages and "Visit <most visited URL>" link as first list item. When I type Y, M or S followed by another letter again a drop-down list appears as is normal. Problem is with those three letters, and clicking "Show history" arrow button next to the address box.

"Did you clean your browsing history recently, in Firefox or using a tool like CCleaner? " No and no. I did nothing that would immediately cause the problem, just visited the pages that I visit every day, no new plugins, no new applications on PC.

You can check for problems with the places.sqlite database (bookmarks and history) in the Firefox profile folder.

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

See also:

• 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

If the Places Maintenance extension can't repair the places.sqlite database then remove all places.sqlite file(s) in the Firefox profile folder to make Firefox rebuild the places.sqlite database from the most recent JSON backup in the bookmarkbackups folder.

• keep a backup copy of places.sqlite in case a new places.sqlite database has to be created
• http://kb.mozillazine.org/Unable_to_process_the_backup_file_-_Firefox

You can use this button to go to the current Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

Start Firefox in Safe Mode to check if one of the extensions ("3-bar" menu button or Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: "3-bar" menu button or Tools > Add-ons > Appearance
• Do NOT click the "Refresh Firefox" button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Thanks, cor-el! Couldn't repair places.sqlite with the plugin, but deleting it solved the problem (at the cost of my browsing history).