Game1go

When I play for about 15 - 35 minutes the screen just goes black, If I avoid it, it keeps doing it until I get off guard and it goes black and I loose a little progress, and I can't exit TechnicLauncher, I then have to restart my computer to have it go back to normal, I am not sure why it does that, maybe I have done something in the setting by accident? Please let me know why it does so.