Show a screenshot of your Memory & Multiprocessing preference settings.
You are also running Photoshop. Does the same thing occur if you are not running Photoshop?
Does the same thing occur if you are not using Render Multiple Frames Simultaneously multiprocessing?
Photoshop just happened to be open when I took the screenshot to post here, but I wasn't running After Effects at the time, I just launched it to grab the screenshot. I can't tell for sure, but I think it only happens when multiprocessing is on.