As an IT engineer, I have had dozens and dozens of folks (students, clients, user group members, associates, friends) come to me with major issues due to MacKeeper. It is a horrible, horrible rip-off of an app.
FIVE of my folks lost ALL of the data on their boot drives. The MacKeeper folks would not offer any tech support other than "You must have done something wrong, do a fresh install."
MACKEEPER is horrendous trash that even Apple themselves should warn against!