Do you see the favicon on the location bar if you visit those sites?

Start Firefox in Safe Mode to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

You can check the browser.chrome prefs on the about:config page.

• browser.chrome.favicons
• browser.chrome.site_icons

• http://kb.mozillazine.org/about:config

The favicons on the location bar (I assume this is what I called "address bar", I'm not completely familiar with the terminology) load just fine for all those sites.

I tried what you suggested about starting in Safe Mode with the default theme, but no luck.

Both those values in about:config were set to "true".

I've found a fix (or walkaround): If I got to my History and do a search for the site, some entries show the favicon and some don't. If I delete the entries that don't show the favicon (so far there has only been one entry per site that doesn't show it), then it starts showing up on the address bar drop-down list.

I still don't know if this is going to happen with new sites that make it to the most visited list.

Thanks for your time, cor-el.

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

• 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

You can try to check and repair the places database with this extension:

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

Done. Hopefully the problem won't return. Thanks again.