How did you save the profile for her data?

I saved the profile, uninstalled FF, and installed the latest version. But when I tried starting FF I got an error message: Your Frefox profile cannot be loaded. It may be missing or inaccessible.

https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

Firefox needs to not be running and the profile folder names must match exactly for this to work, including the random string of 8 characters if this is the method you used.

How did you save the profile for her data?

Actually, I only copied the bookmarks to an ordinary folder on the C disk. Then I uninstalled the old version of firefox.

to James: I had completely uninstalled FF.

This was an odd occurrence: I had run into this piece of malware before. That time I used the Task Manager to kill Firefox. Then rebooted and brought up FF again, and everything worked fine.

This time, though, the malware was persistent. As soon as I restarted FF, I got the same set of multiple flashing windows.

This in spite of having an active antivirus (ESET) running.

ISTM that when I install the latest Firefox and start it, it should create a new profile with the default settings.

What I want to accomplish: 1. Get the latest Firefox working on this (my wife's) computer. 2. Copy the saved bookmarks from the old FF to the new one. If necessary I'll paste each URL into the new FF and create a fresh bookmark from it.

to James: I had completely uninstalled FF. This was an odd occurrence: I had run into this piece of malware before. That time I used the Task Manager to kill Firefox. Then rebooted and brought up FF again, and everything worked fine. This time, though, the malware was persistent. As soon as I restarted FF, I got the same set of multiple flashing windows. This in spite of having an active antivirus (ESET) running. ISTM that when I install the latest Firefox and start it, it should create a new profile with the default settings. What I want to accomplish: 1. Get the latest Firefox working on this (my wife's) computer. 2. Copy the saved bookmarks from the old FF to the new one. If necessary I'll paste each URL into the new FF and create a fresh bookmark from it.

Hello!Delete Old FIrefox Data in firefox and uninstall firefox.Then,Reinstall it.The reason it might happen is probaly because the profile is corrupted already and firefox data is corrupted.Create a new profile and paste each URL into the new FF.Another reason if probaly because one of your bookmarks is the reason this is all happening.Since bookmarks can run code

I just tried this. Uninstalled Firefox. Deleted the folder that should contain Firefox data. Tried reinstalling. Same error message.

Then created new, empty folders named "firefox" and "mozilla". Reinstall again. Same error, but this time it didn't wait for me to start Firefox - I got the message from the installer. Note: my installer is 364KB, downloaded Feb 11, 2025.

I have had a similar problem in the past and out of sheer exhaustion from trying to solve the problem, I finally ran tweaking.com pro in safe mode. Prior to doing that I had cleared every anything I could find to clear (history, clipboard, etc), I had shredded all the trash, run CC cleaner, scanned with Webroot repeatedly through all of this, performed multiple drains of ram etc (machine off style), and restarted after each. It was only after I ran every tool in tweaking.com that I had success with reinstalling FF. I just chose to let it fix everything it could find while it was at it. With an 8TB drive almost 85% full, it took a LONG time; but, it was worth it. I have no idea if this will help your problem or not. I can't even explain what was fixed that made it successful. I have been running computers since 1988 but I have little to no knowledge about what makes them work. You could call me a total numbskull on the subject. That is why I rely on fix-it stuff like "tweaking.com". That was recommended to me by Brian on his YT channel known as "Britec 09". I can't even begin to remember how long I have used this software; but, it has NEVER failed to pull me out of any of the "computer disasters" I have experienced. Don't know if this will help you or not but might be worth a try if you still don't have a fix. Wish you well. Rusty