A continuous monitoring system for regulating access to a computer system or other restricted environment is disclosed. The system employs real-time face recognition to initially detect the presence of an authorized individual and to grant the individual access to the computer system. In some embodiments, the system also employs real-time face recognition to continuously or periodically track the continued presence of the authorized individual. Access to the computer system is revoked when the individual's presence is no longer detected. In other embodiments, the system employs a screen saver program to deny access to the computer system when a predetermined period of user inactivity is detected. Other aspects of the invention include a stranger detector which warns the authorized individual of the approach of an unauthorized individual, a multimedia messaging center which permits unauthorized individuals to leave messages for authorized individuals, and an adaptive enrollment program which permits the system to update the stored video images of authorized individuals to reflect the individuals' current appearance.