Sometimes in Immersion or Strengthening I get big black panels appearing either side of my screen which last, like, a second then vanish. Sometimes they appear on top of the sentence on the screen. Is this Duolingo or my computer? I use Mozilla firefox.
Would you edit your post to include what operating system and browser you're using? It's always good to include that in every troubleshooting post. :)
My bad! I usually post an example, such as Windows7/Chrome. I forgot to. My computer laptop has a little blue sticker on it that says Windows 7, can you find anything with a number? The different versions of Window matter, I think. (I'm not part of tech, so, guessing on that part.)
What the computers uses to run the system. Windows, Osx, and linux are operating systems. If you really don't know read about it on wikipedia!