I found that if I add a lot of files to one of my apps (bookman) using iTunes, it appears to sync the files successfully (automatically) and then... when I next try to open Bookman or any other app, it just doesn't work! A soft reset seems to be required, then things go back to (reasonably) normal. But this is quite disappointing... surely the damn thing should operate normally when you do something normal like sync some files into it???