Try these suggestions; (1) Disc Utility, repair permissions (2) Reset Pram (restart holding down option+command+p+r keys until you hear chime twice, then let it start (3)As for users, tell your wife to log out when she is finished with the computer! (4) Have a password for yourself as admin and set your wifes account as standard so you have responsibility for the software
etc. (5) First 90 ...