Diễn đàn hỗ trợ Firefox

Windows 10. Weird glitch.

If I use Wondershare UniConverter's downloader function to download a video, as soon as the download starts, all Firefox open windows close. This is a recent thing, the last couple of weeks or so. I have reinstalled Firefox and UniConverter. The first time I tried it after reinstalling UniConverter, all was well. But the same issue has shown up again. I have tried rebooting my PC to no effect.

Any bright ideas welcome!

There seems to be something specific to the Phlearn site and Firefox which prevents videos from auto advancing. They either recommence the just completed video or revert to an earlier one.