my browser won't work properly since update 150 and 151

I open Firefox, my browser, then I type in the site I want to open. It opens fine, however, when I try to open another site I want to open nothing happens except a little dot in front of the requested site keeps going back and forth, but nothing opens. I then have to close the browser, re-open the browser and key in the site I want. WHY? What am I doing wrong. Please keep in mind that I am not a computer savvy person and don't understand much about them. I do know however that Firefox used to work on my computer before update 150 and 151 were downloaded without a hitch. I have tried everything I could think of to fix the problem without success. I am beyond frustrated and need this fixed.