I too was getting that AOL popup about a core update. I contacted AOL about it and was told that it was in fact legit and to go ahead and install it. I had put off for about 2 weeks paranoid that it was spam or even a virus. I did the virus and spam check and everything came up clean with it. So I did finally install it and thankfully my pc is working fine. I haven’t had even any minor or major things happen. Nothing has stopped working or acting weird. So my suggestion would be to chat with a consultant from AOL before installing it if it happens again. I was lucky this time.