Software program that prevents tampering with (changing) the computer clock
Editor: Clock Guard is a Windows 95/98/2000/ME/XP/NT/Vista software program that prevents tampering with the computer clock. It can be used for various purposes. A few examples are:

1) Preventing files from being given falsified time/date stamps by manually resetting the system clock and then saving the file.
2) Prevent employees who are using a computer-based time clock from altering the time to allow themselves to Punch in at a falsified time.
3) Prevent users who have time limited programs (programs that can only be used at certain times) from accessing these programs at improper times.
4) Prevent people who are paying for computer use on a time basis from resetting the clock to reduce the amount of time they pay for.
5) Prevent people who are restricted to a certain amount of computer time per day (usually children) from resetting the computer clock to give themselves more time.

you can free download Clock Guard 8.7.0 now.