well, sorry to hear that, my duo had this problem, and another thing i remember doing, is updated the bios, mine came with the a01 version and updated to a06, found this update on the dell page.
My duo works very well now, but sometimes i still hear a little glitchy sound when playing mp3, i think it is a problem of a processing priority in the sound device, but well, now it is almost innotticeable.
sorry for my english, and hope that info helps. saludos.
pd. if you send the duo to repair, id like to know if a new duo was the solution for you, maybe this is a hardware related problem with mine too.