There are several possibilities. This is the most recent problem;

Could this be relevant? A couple of other users identified Webroot (security software) as blocking 64-bit Firefox 97 -- released today -- from running properly:

• https://support.mozilla.org/questions/1367248
• https://support.mozilla.org/questions/1367301

If you are still running an earlier release of Firefox, this would not be your issue.

Some problems occur when your Internet security program was set to trust the previous version of Firefox, but no longer recognizes your updated version as trusted. Now how to fix the problem: To allow Firefox to connect to the Internet again;

• Make sure your Internet security software is up-to-date (i.e. you are running the latest version).
• Remove Firefox from your program's list of trusted or recognized programs. For detailed instructions, see

Configure firewalls so that Firefox can access the Internet. {web link}

Thanks for the response, I've disabled Webroot and that seemed to help a little. But Firefox, despite being refreshed yet again is either no responding, opening multiple tabs, or very slow to open and then not responding. I've worked through setting up the firewall to allow Firefox to operate properly. Not sure what to do next.

. . . . opening multiple tabs . . .

What is being opened? What is in the tabs/windows?

Start Firefox using Troubleshoot(Safe) Mode {web link}

A small dialog should appear. Click Start In Troubleshoot(Safe) Mode (not Refresh). Is the problem still there?

https://www.mozilla.org/firefox/97.0.1/releasenotes/

Fixed Works around problems with WebRoot SecureAnywhere antivirus rendering Firefox unusable in some situations