Hi - thanks for the effort! I added the following (and am including my actionresult jsut in case) - still got the same error so I guess it's not the "refreshing of the database idea" - I must be doing something else fundamentally wrong...

private ObjectContext _objectContext;
        private void RefreshExecute()
        {
            _objectContext = ((IObjectContextAdapter)db).ObjectContext;
            _objectContext.Refresh(RefreshMode.StoreWins, db.SetLists);
        }
 
        public ActionResult AddSongToSetList(int setListID, int songID)
        {
            db.SetListSongs.Add(new SetListSong { SongID = songID, SetListID = setListID });
            db.SaveChanges();
 
            RefreshExecute();
            var setlist = db.SetLists.Find(setListID); 
 
            ViewBag.UserID = new SelectList(db.aspnet_Users, "UserId", "UserName", setlist.UserID);
            ViewBag.BandID = new SelectList(db.Bands, "BandID", "BandName", setlist.BandID);
            ViewBag.Songs = db.Songs.Where(s => !(db.SetListSongs.Where(o => o.SetListID == setListID).Select(o => o.SongID)).Contains(s.SongID));
 
            return View("Edit", setlist);
        }