I believe it has to do with Microsoft not supporting Windows 7 as they should because trying to get people to move to Win10. (ripe for a class action suit) Not much you can do about it other than to make sure you are updated with all Hardware Drivers (which Win10 will change if so wants to, a fix for that) all MS Updates. A lot of people on Win7 have moved to the Extended Release version as Firefox updates break Firefox on Win7 as you have just experienced. https://www.mozilla.org/en-US/firefox/organizations/all/

Please let us know if this solved your issue or if need further assistance.

Are you running Firefox 56 right now and it works fine, but when you had Firefox 56 before, it had stopped working?

I'm not sure what went wrong there. Do you recall the message you got about firefox.exe in more detail?

Pkshadow: Firefox ESR works perfectly! Thank you!

jscher2000: Thank you so much for responding!

Attached: 2 files

01. Original error message .. (jscher2000) 02. "About Firefox" .. showing the new functioning install (Pkshadow)

I really appreciate the help!