Some months ago I installed Zorin OS 9 (Ubuntu). It all went right since this week, when online dictionary at wordreference.com started to block the audio of the English terms. Here is the message from the system: "MP3 playback not supported. Linux users can install Gstreamer to get support." Now, Gstreamer is fully installed and Firefox is not having the same problem with other sound's sources, like radios and youtube. I tested the audio on Wordreference.com with Chrome, and it run perfectly. The only clue I can think about is that the problem appeared after a recent automatic update. What do you think could have happened ? Thanks a lot. I'm trying to switch to ubuntu/Zorin from Windows and I'm not a very brilliant student; also, I'm not a native English speaker. So, I hope my message will result understandable and I will be very grateful for any patient answer.