Firefox has always made me feel happy. But I am having significant problems with Mac OS version 71.0. I am running a macOS Catalina v 10.15.1 on a 3 GHz Quad-Core Intel Core i5; 16 GB 2400 MHz DDR4. I am NOT having a performance issue. Instead, the browser is not responding as expected when given tasks. 1. It will not open a link in a new tab. The tab does not open and it's as if I never clicked on the menu item. Same with open in new window. 2. It will not open the default search engine from the URL bar. Instead, it responds as if I mistyped a URL. 3. It will not allow me to set a Default Search Engine. The option to do that in Preferences is a drop-down arrow that does nothing when clicked. 4. It will not allow me to Remove an add-on. Usually issues with Firefox are related to add-ons, but when I Remove an add-on, then restart Firefox, the add-on is still there. 5. (silly, minor issue) I'd like the tab bar to be dark, again. The white tabs are too bright! I know this is silly, but you asked... I did run Firefox in safe mode and all of the same problems continue to occur. I did reinstall FF v. 71.0 and all of the same problems continue to occur. Help. Please.