i had this problem also.. i had tried copy the scriptaculous folder to js directory,but it wont work.. actually,the widget runs okay before this, then suddenly it goes wrong after i install few more plugins.. i cannot think which plugin may caused it,thus i deleted all plugins(except the default one) including deleting all the tables created(in db) from those plugins.. until now, the widget still cannot be dragged n drop.. it is something related with wordpress cache?? although,i dont have any cache folder coz i dont install wp-cache.
i was thinking to reinstall wordpress… i have tried also using other computers…
im using wordpress 2.0.5, firefox 2.0, windows xp pro and my wordpress are installed on my own pc…