Using the firefox browser as usual on a windows 10 pc and 22in monitor. All of a sudden now when I expand youtube videos to full screen there is a thin white line down the right hand side of the screen. This has never happened before and doesn't occur on chrome or edge. BBC i-player is fine in full screen, so is DailyMotion and the problem only seems to be present on youtube. I noticed that videos emebedded on other websites expand perfectly without the line so it's only on youtube website itself but only in firefox. Not a big issue but you're aware of the line, it having never been there before. The only change to my computer recently was a routine disk cleanup and clearing of the cache using ccleaner. But I've done this before and no problems. Do you think this is a youtube issue or firefox issue? Darren