Quoted from Barry1:The punch button seems to be working normally during play, but at the start of a new ball it seems as if the button is pressed and you never get to use the plunger.
This can happen if any playfield switch closes from the vibrations of the ball ejecting to the playfield, the game basically sees a playfield hit which means there is a ball in play and sees a ball in the launcher so it kicks it back into play. I had a similar problem on my LE which was also intermittent. On my machine the problem was the Vengeance drop target falling without being hit.