There may be a problem pasting into Facebook with duplicate and un-removable text if a setting was changed. Could you check here: (1) In a new tab, type or paste '''about:config''' in the address bar and press Enter/Return. Click the button promising to be careful. (2) In the search box above the list, type or paste '''CLIPB''' and pause while the list is filtered (3) If the '''dom.event.clipboardevents.enabled''' preference is bolded and "modified" or "user set" to false, double-click it to restore the default value of true Some users set that to false due to issues pasting into YouTube comments, but then there are problems on other sites... Did that make any difference?