All I had to do was type about:config in the Address Bar, find network.dns.disableIPv6, right click and select "Toggle" (Set Boolean from False to True), and restart Firefox. And also had to reinstall the Ubufox Extension for Firefox, found in the Ubuntu Software Center.
I am new to Linux Ubuntu and I am having a problem with Firefox Addons. I can access the Firefox Addons website, but when I click any of the "Add to Firefox" buttons, it freezes. And when it does go (slowly) to the Install window, the Installation freezes and says, "Waiting..." below the addon. And then I get Error #228. Ubuntu and Firefox are fully updated, I have Java and Flash installed, and Firefox was pre-installed. Any help would be greatly appreciated.