Maybe I'm missing something that suggests this is a system problem but does all this redness only appear in the browser?
If so, does it still appear when using another browser?
If this is just happening in Firefox were the user profiles deleted when installing the latest version or were they retained? If the latter then backup your bookmarks (and make a note of any other settings that you may have changed deliberately) then uninstall Firefox completely, including the user profiles, before installing the latest version (and then restoring the bookmarks).