A networked public multimedia kiosk based on a personal computer compares key codes resulting from user input with a table. If a key code, or key code sequence, matches an entry in the table, the user input is ignored. This restricts use of the computer by the public. Different levels of access to the computer may be provided by modifying the table through a password controlled security program. For enhanced security, gamma tables (which control the brightness of the screen output) may be set to zero while the operating system of the computer is loading.