The problem is, the trigger actions/locations aren't instantly apparent. It might be entering the area, entering the house, picking up the necklace, picking up the diary, walking out of the house, leaving the location, activating a certain ghost...
If you could use trial and error, you could find out which part you need to do EXACTLY in order to get the game to load the conversation where you can return the necklace, and skip the rest.
The protean power might help, I dunno, I can't see whats going on with your monitor. You'd be suprised how cheap monitors are to fix/replace these days, but assuming that isn't an option... Yeah, I'm a little short other ideas.