hi Stocker63, this is a long-standing false positive detection by norton's product deleting integral parts of the firefox installation folder,which they know about for months - but apparently norton is not able to fix it in a timely manner: https://community.norton.com/en/forums/problem-firefox-3601-update please look into your norton's configuration to see if something can be done about this (maybe whitelisting the mozilla firefox folder) or otherwise use a more reliable and unerring security vendor.

This is something that Norton software has been doing with the SeaMonkey suite for like four plus years now and yet to fix it. This false positive happens every so often on Firefox also over the years, not months.

SeaMonkey has been mentioning this Norton problem in known issues part of Release Notes for a few years now as Symantec has not fixed it permanently yet. http://www.seamonkey-project.org/releases/seamonkey2.39/

Norton/Symantec anti-virus scanners may report that some parts of SeaMonkey (e.g. the file freebl3.dll) are suspicious. If you downloaded SeaMonkey from one of the official download sites, this is a false alarm. You might experience problems with secure websites when this happens. To fix the issue, instruct your anti-virus software to ignore these files (and move them out of quarantine) and/or switch to another anti-virus software and reinstall SeaMonkey.

The above may not sound like to be related to same thing but it is.