First, thank you for pointing out that you can move a downloaded file from its original location to a new one by dragging its entry from the downloads window. If I hold the Ctrl key while dragging, it copies to the new location. This is handy.

This sounds obvious, but if you aren't having Firefox clearing history, and you don't have any third party software clearing your history, and you're not in private browsing mode, then your list shouldn't be cleared...

In addition to the "real time" setting of storing history, make sure you don't have Firefox set to clear downloads at shutdown.

orange Firefox button or classic Tools menu > Privacy

If you switch to "Use custom settings" you can make sure that "Clear history when Firefox closes is not checked" (or if it is, that Download history is not selected for clearing).

Can you think of any third party software that might be cleaning up your history?

By the way, a few other things you probably know:

(1) The setting to keep the downloads list displayed after a download is here:

orange Firefox button or classic Tools menu > Options > General

Check "Show the Downloads window..." and uncheck "Close it..."

(2) You can always show the list by pressing Ctrl+j

The mimeTypes.rdf file isn't particularly relevant to this problem; it affects what application Firefox uses to open a particular type of file.

However, there is a database file which stores your download history which might be corrupted. You could rename that file and have Firefox start building a new one.

(1) Open your personal settings (AKA Firefox profile) folder

Help (or Alt+h) > Troubleshooting Information > "Show Folder" button

(2) Switch back to Firefox and exit the program (e.g., File > Exit)

(3) Wait a few moments for Firefox to finish updating files in your settings folder, then rename downloads.sqlite to something else, like downloads.old. Alternately, you can delete the file.

(4) You're done with your profile folder and you can restart Firefox now.

Any improvement?

One other thought: if you installed any add-ons which alter or take over the download list, you might need to disable them to restore normal functioning. You can check your plugins and extensions here:

orange Firefox button or classic Tools menu > Add-ons

@jscher2000

First, I appreciate all of your feedback.

Second, funny how little tricks are passed on...

Regarding your ideas, I had run through pretty much everything already, checking and rechecking settings.

I did delete the downloads.sqlite file but no luck there.

I cannot think of any third party software that would clear the downloads manager window.

The one thing that I did suspect was the one add-on I have: Adblocker Plus. However, I disabled it and the same results.

Maybe FF is corrupt and needs to be reinstalled...

Hmmm...

If you have any other ideas I'm game....

Did you check this setting?

• Tools > Options > Privacy > Firefox will: "Use custom settings for history" > "Remember download history"

• https://support.mozilla.org/kb/Downloads+window

You can also manage and inspect all downloads in the Downloads folder in the History Manager (Library)

• History > Show All History

Note that future Firefox version no longer will use the classic download manager, but will use a toolbar button to open a drop down list.

@cor-el.

Yep, Did the custom setting too. No luck.

The "issue" with looking at downloads in the History>Show All History window is the list does not have the actual files, rather the internet address for the file. So, a simple drag and drop does not work.

Thanks for the feedback.

If you have the files in the (classic) download manager window then you can open the containing folder via the right-click context menu to move the file to another folder (you can only do this if the file is still in the original folder).
The file should show there if you keep the download history.

@cor-el

That has been the problem... the files do not remain in the folder even though all of the (known) settings are to keep the download history.

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

• Do not click the Reset button on the Safe mode start window or otherwise make changes.

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

You can check for problems with preferences and try to rename or delete the prefs.js file and possible numbered prefs-##.js files and a possible user.js file to reset all prefs to the default values.

• http://kb.mozillazine.org/Preferences_not_saved

Well, it's fixed.

The problem appeared to be an outdated plug-in, likely the previous version of Adobe Reader.

Tools>Add-ons, Plug-ins page.

All is well now.

Thanks to everybody that helped.