ROTOBRUSH ISSUE RANDOM GREEN PIXELATED FRAMES

theboys.mp4 that you have selected may have some decoding issues. The frame rate matches Precomp 3 so that's a plus but there could be other issues. When I have problems like this the first thing I do is render a suitable visually lossless production master from the MP4 making sure to use an industry-standard, frame-based format line ProRez or Cineform. Then I replace the footage in the timeline with the DI (digital intermediate) that was created.

Your comp also looks like it's several seconds long and Layer 3 looks like it is about 4 seconds long. You could be running out of system resources.

I also noticed that you have one MP4, the third from the top of the Project panel, which is a very odd frame rate, and that the footage, Pre-comp 3, and the main comp do not share the same frame rate. It would be a very good idea to match up the frame rates, especially if you are doing Rotobrush work. If an MP4 has any kind of odd frame rate it should be conformed to the closest standard frame rate using Interpret Footage.

Try updating or rolling back your graphics driver directly from the video card manufacturer’s site.
If NVIDIA, make sure to use a Studio Driver, not a Game Driver.