Safari Won't Force Quit & Suddenly Stopped Functioning

My Safari browser has just gone completely wonky. I can't force quit it at all using every conceivable method. And even when I have successfully forced it to quit and rebooted, the same problem occurs. Sometimes the browser starts up and seemingly starts functioning, then the evil beach ball appears. In another instance, the browser up long enough for me to empty the cache. Still no avail.

My Macbook Pro keeps getting a pop-up that "Safari can't open because it's not functioning." See attached. It's gotten to the point where I'm not going to spend any more time trying figure this out and switch to Chrome permanently. I've tried everything literally on any forum I can find, but to no avail. Nothing changes.