Haptic feedback turns on only when I insert the jack... why?

My phone (Galaxy S II) is behaving in a rather strange way: haptive feedback seems not to work even when the battery is full, the "haptic feedback" checkbox is checked and the phone has been rebooted several times. The most strange thing is that haptic feedbeck turns on again when the earphones jack is plugged in(!) and turns off when I remove the jack. Is there any chance thant I will ever have my haptive feedback back unconditionally? Any suggestion? Thank you very much...