Good day. I've used Firefox for decades and love it. System: Macbook 2012 - OS 10.15.7 Catalina (most current Catalina version) 16G ram, Intel guts Firefox - 121.0 (64bit) About a month ago it started quiting within a minute of being open. I would open it again, then it would quit within a few seconds. I would try to open it again and it would show the little black dot beside the icon in the dock for a second or two but not open at all. None of these "crashes" would generate a crash report and there was no error message. I could start it again in troubleshooting mode (hold shift + option) but it would only last about 20 seconds before closing again. This is repeatable meaning I can keep opening it in troubleshooting mode and it will keep closing. It generates the window "Open in Troubleshooting Mode?" with options of refresh or open. When I open it, it gives the option of new session or restore old session, both options work, then quit. Things done: most of these have been done multiple times Turn machine off and on - sometimes opens for a bit sometimes no. Safe mode - as above Open in a different Mac profile - no change. Refreshed Firefox - sometimes opens for a bit sometimes no. Reinstalled Firefox - deleted the app then new app - works for a bit then same Disk Utility checked all volumes Clean install - removed all Firefox bits that I could find using AppCleaner and also searching in Finder - no change Reinstalled most current version of Catalina - Firefox worked for about 2 minutes, then same. Made a new profile, deleted other profiles - worked best for about 15min then back to same. Other info: Safari works fine. Firefox on my Galaxy phone works fine Thanks for any suggestions Phil