When I moved into my first house I had the oddest feeling that things weren't right when I got home from work every day. One day I got a call at work from my neighbour, to tell me that the electrician had fallen downstairs in my house "right at her feet." When I asked her what she was doing at the bottom of my stairs she sounded surprised and said 'didn't you know I was keeping an eye on the place for you?' Over the next few months she commented on my husband's underwear, what was in my fridge etc. so we changed the locks. Then I had a call at work asking me where the spare key was because she wanted to borrow something. No matter what we said, she seemed to have no idea that this wasn't acceptable.
It got worse when I had my first baby - if I left him in his pram in the garden for a nap she would pick him up and take him to hers!
We moved as soon as we could.