I'm not an expert on this stuff at all, but a few reasons why this could be happening: 1. Maybe the computers think there are too many files in that one folder, so it begins removing some to make up space 2. Your computers may possibly have Cloud, or something similar, that is transferring the files over and not knowing what to do with them That's just what I am thinking, but then again, I'm not the smartest with this stuff lol Hope you figure this out!