A computer may be secured from attack by including a trusted environment used to verify a known monitor. The monitor may be used to determine a state of the computer for compliance to a set of conditions. The conditions may relate to terms of use, such as credits available for pay-per-use, or that the computer is running certain software, such as virus protection, or that unauthorized peripherals are not attached, or that a required token is present. The monitor may send a signal directly or through the trusted environment to a watchdog circuit. The watchdog circuit disrupts the use of the computer when the signal is not received in a given timeout period.