hello gfjenner,

if your home page also gets changed, could you start here:

One possible culprit would be an extension. You can view, disable, and often remove unwanted or unknown extensions on the Add-ons page. Either:

Ctrl+Shift+a (Mac: Command+Shift+a)

"3-bar" menu button (or Tools menu) > Add-ons

type or paste about:addons in the address bar and press Enter/Return

In the left column of the Add-ons page, click Extensions.

Then cast a critical eye over the list on the right side. Any extensions Firefox installs for built-in features are hidden from this page, so everything listed here is your choice (and your responsibility) to manage. Anything suspicious or that you just do not remember installing or why? (Don't assume their name will advertise their bad behaviors...) If in doubt, disable (or remove).

Any improvement?

Regarding losing additional search engines you added on, that definitely shouldn't happen. Once you have it set up the way you want, please make a backup of the settings file for search engines, as follows:

Open your current Firefox settings (AKA Firefox profile) folder using either

"3-bar" menu button > "?" Help > Troubleshooting Information (menu bar) Help > Troubleshooting Information type or paste about:support in the address bar and press Enter In the first table on the page, on the Profile Folder row, click the "Open Folder" button. This should launch a new window listing various files and folders in Windows Explorer.

Find search.json.mozlz4 and right-click > Copy it, then Paste somewhere malware isn't likely to look, such as your Documents folder. In the future, if this happens again, you could replace the new file with your old one to restore your current search engines.

Finally, please be advised of a potential program folder infection caused by the installation of the program Lavasoft Web Companion. More on that in this thread: https://support.mozilla.org/questions/1198173

I hope resolved the problem click Chosen solution

Thank you!

Hi gfjenner, you mentioned some data types but not others: are bookmarks and saved logins preserved? How about any add-ons you installed?

One possibility is a Refresh. When Firefox performs a Refresh, your old profile folder with all your data is moved to your desktop inside an Old Firefox Data folder. Have you noticed anything like that? If so, hang onto it for recovery purposes.

The only extensions showing enabled are one for LastPass and another for private bookmarks. Neither is new.

As for Jscher's question, nothing else seems to change when FF restarts.

It's certainly possible that a crash is occurring which is severe enough to corrupt some data files. However, if there's no pattern to it, it's difficult to make specific suggestions.

Does the Mozilla Crash Reporter dialog appear when Firefox closes? You might have some crash report info. This article describes how to find report IDs for those crashes: Firefox crashes - asking for support.

First, I want to say thanks for helping.

No crash report appears. Today, for example, I had a series of research windows open plus a half-finished Mega-Sudoku puzzle. My battery had dropped to 20% so I plugged it back in. An hour or so later, all the windows are gone and the only open window is the FF default home page (not mine). So I would not describe it as a crash, but something does seem to be triggering a restart that wipes out existing windows, my chosen home page, and my chosen search engine.

Is there a way to see if something was downloaded within the last week or so (when this happened for the first time)?

When this occurs, is session restoration possible? Either:

• "3-bar" menu button > Restore Previous Session
• (menu bar) History > Restore Previous Session

If those are missing or grayed, either:

• "3-bar" menu button > Library > History > Recently Closed Windows
• "Library" toolbar button > History > Recently Closed Windows
• (menu bar) History > Recently Closed Windows

Is there a way to see if something was downloaded within the last week or so (when this happened for the first time)?

Well, your Firefox download history would be Ctrl+j.

In the Windows control panel, "Uninstall a program", there may be a way to sort by install date.

For extensions in Firefox, the installation date is hard to find, but I think you already checked those and didn't see any surprises.

I'm afraid I could not restore my previous session.

BTW - I should note this is a Mac.

I was thinking it might be possible to go back in time two weeks.

BTW - I should note this is a Mac.

Sorry, I forgot. So Command+j for downloads in Firefox? Not sure how MacOS tracks software installations.

I was thinking it might be possible to go back in time two weeks.

Using a Time Machine backup? You might want to back up bookmarks in case you lose something useful rolling back (there are two possible formats and I always suggest creating both):

• JSON format: Restore bookmarks from backup or move them to another computer
• HTML format: Export Firefox bookmarks to an HTML file to back up or transfer bookmarks

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:77.0) Gecko/20100101 Firefox/77.0

Are you sure that Firefox is actually installed?

Too many Mac-users have been launching Firefox from the DMG file rather than from the installed Firefox program. I have seen that so often that it has to be considered when the Original Poster here says "It wipes out all my exiting windows, changes my default home page, and changes my search engine." When that is done nothing is saved, it's like a new installation every time Firefox is opened from the DMG file.

https://support.mozilla.org/en-US/kb/how-download-and-install-firefox-mac

Sorry if that isn't the case and it doesn't help you, but I want to "cover all bases". I am not a Mac-user myself but sometimes I follow some Mac related support threads - Justin Case ...