I got the phone on release day. After spending about 5-6 hours setting everything up, it happened to me. I knew I'd been in the security settings before so started uninstalling apps . When I got to the TeslaUnread (add-on for Nova launcher), uninstalled and security settings no longer crashed. Re-installed crashed, etc. Everything has been fine (I thought) until tonight I needed to go into the security settings again and again got the "Unfortunately, settings has stopped" message. I have no idea what I may have installed since Oct! I tried getting rid of a few things I know I installed over the past week, but beyond that, no idea.
Google'd a bit (was nothing anywhere yet when it first happened to me) and found this -
PSA: Settings > Security "Unfortunately, Settings has stopped." [SOLVED] : galaxynote4
For the heck of it I removed the S-View cover and settings did not crash when I opened Security Settings. Put it back on and it crashed upon opening it, etc. Definitely was not the issue the first time because I tried this then. Ugh. Hard to believe there's only like five of us on the whole darn web!