Mysterious alarm in trc 4

I am at the moment flying the TRC 4. Like the other three it's great and a tremendous help in improving my understanding of the 747 systems.However, I'm encountering a problem that's slowly driving me crazy.When I load up TRC4 part 1 for the first time, everything works fine. But when I reload this lesson,set the autobrake and take off again an alarm goes off just when I leave the runway. There's no message in the eicas or anywhere else, all the anunciations are correct, the speed is fine. This happens everytime I reload the lesson. I can switch the alarm off, of course, but I really would like to know if anyone has an idea why it's behaving like this.Martin