Definitely the security module. It may have a loose connection or your car battery or alternator may not be up to spec and it's causing a lack of power situation at the alarm module. I worked for a remote starter and car alarm producer(JBS Technologies) as a technician for 2 years, And I know from experience that electronics like alarm systems don't like not having enough power. Believe me, I've heard much stranger stories than yours due to bad connections and bad alternators.
