Hey, I have a MZ-N710 and havent had any trouble untill about a year after i bought it when it started stopping and going to a totally different track i ignored this as i thought it may be something to do with the fact i ride my bike a lot. Recently though the sound has severly taken a turn for the worse as very small movements affect it and sometimes the sound only comes out of one side. I got some new earphones thinking they were the problem ... it turns out they werent. I've been looking around to see if people have been having similar problems i just hope it isnt something serious like the laser!!