Let's try this first, Places Maintenance {web link} Allows to run Maintenance tasks on the database that drives Places, the bookmarks and history module behind Firefox.

Open the Add-ons Manager. Locate the add-on and press the Options button. Then follow the directions.

Good idea, but it still doesn't let me drag & drop the shortcuts.

Can you at least drag a Tab to the Bookmarks Toolbar?

Do you see any bookmarks on the Bookmarks Toolbar?

Do you get the "no dropping here" indicator (circle with a slash), or what exactly happens?

On Windows 7, I can drag the little i-in-a-circle icon and drop it on the Bookmarks Toolbar. With the text of the address, I need the entire thing selected in order to drag and drop a valid bookmark.

No, I can't drag the "i" in the little circle nor can I drag a tab and selecting the whole address makes no difference either.

Also, I don't get the "no dropping here indicator".

I can add bookmarks with the "star" icon, which works okay, I'm just really used to dragging dropping them.

Let’s do a full clean re-install; Download Firefox For All languages And Systems {web link}

Save the file. Then Close Firefox.

Using your file browser, open the Programs Folder on your computer.

Windows: C:\Program Files C:\Program Files (x86)

Mac: Open the "Applications" folder. https://support.mozilla.org/en-US/kb/how-download-and-install-firefox-mac

Linux: Check your user manual. If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it. See Install Firefox on Linux; https://support.mozilla.org/en-US/kb/install-firefox-linux

If you downloaded and installed the binary package from the Firefox download page, simply remove the folder Firefox in your home directory. http://www.mozilla.org/firefox#desktop ++++++++++++++++++++++++++++ Do Not remove the profiles folder.

Look for, and rename any Mozilla or Firefox program folders by adding .old to them. Do not rename the Mozilla Thunderbird folder if there is one.

After rebooting the computer, run a registry scanner if you have one. Then run the installer. If all goes well, remove the OLD folders when you are done. +++++++++++++++++++++++++++ If there is a problem, start your Computer in safe mode and try again.

http://encyclopedia2.thefreedictionary.com/Linux+Safe+Mode This shows how to Start all Computers in Safe Mode; Free Online Encyclopedia

Wow! I really had high hopes for that solution, but still no luck. This is a new computer running windows 10 with the McAfee LiveSafe that came with the computer. Could it be something with the AV software?

Finally, on the second reboot, it's working. It seems the complete re-install was the solution after all. Thanks for the help

Glad to help. Safe Surfing.