I have probably been using Firefox for 20 years and up until this past year I never had a problem. I am now constantly running across sites that I cannot access or do not work on Firefox. I wish I had kept a list because it would have been a long one. It has gotten to the point that I am considering using another browser for my default. I have tried getting this question answered several times and have gotten no response. If I do not get one soon, I will have to drop Firefox as my default browser. This is not a problem that I have had on just one computer, but on all 5 that I use.
