DosStopTimer stops either a repeated-interval timer (started by DosStartTimer), or a single-interval timer (started by DosAsyncTimer).

When DosStopTimer is called, no assumption can be made about the state of the event semaphore that is associated with the timer. If the application is going to reuse the semaphore in conjunction with another timer, it should issue DosResetEventSem to ensure that the semaphore is in the "reset" state before starting the timer.