As I know Windows Movie Maker is long gone, I am getting a new editor soon, I still need help with it till I get a new editor.

Windows Movie Maker was working perfectly fine saving videos and such, until I decided to make custom settings. They were all the same settings as the recommended settings, but I changed it from 29.97 FPS, to 60 FPS, and after completion of saving, it went black in some parts of the video after the 10 minute mark.

I also just discovered, before saving, some parts of the video are black w/ audio running, and some video files are grey, but no yellow triangle, and still run the audio. Though when I save it in recommended settings, it changes and the whole video actually shows the video.

I've installed K-Lite codecs pack, nothing, I repaired Windows Essentials 2012, nothing, I have even installed the up-to-date video/graphics card driver, still nothing. I've done basically everything Windows has said to fix the problem.

I am using .avi files, and I am leaning towards a problem with that, but this never happened till I switched to Windows 10 Pro.

I am either assuming it isn't completely compatible with Windows 10 anymore, or it's something so tiny, I can't figure out.

I will supply my computer specs if you need them, but yeah. If you can even just lean me towards a safe file converter software, as I have tried to do that, but most seemed like viruses and such. 

If someone could reply to me as soon as possible, that would be great.