Watch video. This has happened before, but its not until recently that it happens 1 out of 2 rooms. Then I have to restart NF again, and it happens after every other battle. Happens when in GB. HA, or any room that isn't training room. I use windows 10, and I set compatibility to windows 7. I also have already reinstalled NF, and no fix.
https://www.youtube.com/watch?v=kXfm9ARZLfQ&feature=youtu.be