Patent ID: 8190923

Claim:
A method of protecting a timer on a pay for use computer system from being improperly adjusted, the method comprising: establishing a baseline value for at least one timer on the pay for use computer system wherein a user pays for a time period of use of the computer system; determining threshold frequency differences; monitoring the pay for use computer system for a timer anomaly that indicates a possible improper timer adjustment by: determining a set of timers in the computer system; including the at least one timer; periodically obtaining current operating frequencies of each of the timers, respectively; repeatedly computing a current set of frequency differences by computing a difference between each of the current operating frequencies of the respective timers such that the current set of frequency differences includes a frequency difference between each timer and every other timer; detecting a timer anomaly by repeatedly comparing the frequency differences in the current set of frequency differences against the threshold frequency differences, respectively, and determining that a timer anomaly has occurred when one of the threshold frequency differences is exceeded by a corresponding current frequency difference; imposing a sanction if the timer anomaly is detected wherein the sanction comprises limiting functionality of the computer system and leaving the computer system in a reduced functioning operating state.