I have been using Firefox for years with never a problem. But today, and only on my main computer, I have problems. First it would not load any website I visited. It would time out and say "server took to long to respond". Then it started to load the sites again but many websites (including Experts Exchange) Firefox would display a certificate warning. See images I uploaded. I had to revert to Internet Explorer to be able to cruise the Internet. Now strangely enough, Firefox on my second computer works fine with none of these problems. Both are running Windows 7 and the Firefox versions running on both computers are the same. What should I do?