I am using MS Security Essentials and use this on all of my machines, have been for many years so doubt that is the problem. Nothing fancy, default settings in MS Security Essentials. Also worth noting i've got versions 15, 16, 19, and 20 that do not have or ever had this issue on same machine. Not sure what else i can provide but happy to do so just let me know. Curious to know what those 2 lines you mention are related to.
Thanks.