I can get both my F75's (orig & LTD) to do that in certain places. Or that machine may have needed to be rebooted. Every time a sensitive machine comes out, people seem to complain about "interference". All sensitive machines, if not tuned properly, will be noisey! If its chattering, you dont have it set properly. Even at a Sens of 10, the machines are hot. With the F75, to really make it work to your advantage, let the machine tell you where to set everything. Turn the Sens down until the machine is stable, no matter what that number is. Switch freqeuncies. Try running in All Metal (that really quiets the machine down). You might be surprised.