iPad and/or iTunes have mind(s) of own: they delete playlists that are on one or the other at random, sometimes (but not always) refuse to sync in one or the other direction, capriciously and persistently delete 3 particular songs from only 2 of the playlists I've put them on (these 3 happen to be among my current favorites....coincidence? I think not. I suspect malice aforethought).  I know I totally sound like this (prolly not entirely SFW.... the computer is not very nice).