iwork10 darkens the screen when using. How fix it?

I’m sorry my english. I’m having trouble with my AlldoCube Ultimate Iwork10 ii5t Laptop. The screen turns black whenever I use it to watch videos or when I’m in class. It stays black for a couple seconds then goes back to normal. While it’s black, the audio still works fine. This only happens on the Windows side. on the Android side, it works perfectly normal. There were times when I was working on assignments, and lost all my work because of the screen turning black. So, I’d like fix this problem because it bother me.