I used to live in a flat in an large old house with 2 friends, we were also mates with the people who lived upstairs. When we first moved in I thought one of my flat mates was playing tricks, moving stuff around, there was knocking at the front door and no one there, strange noises in the hallway, I didn't take it seriously even though As time went on I thought could feel a certain "presence" in the flat when i was on my own.
One night I got home late from work and there was lots of noise coming from upstairs, it sounded like they were moving furniture around and stomping up and down the hallway, I was in my room when I heard my flat mates get back from the pub and all the noise from upstairs stopped. I mentioned how noisy it had been, but my flat mates were surprised as apparently there was no one upstairs as they all been up the pub together.
Then a couple of nights later I was again home alone and watching the tv when I "felt" someone walk into the room and sit down next to me on the sofa, I swear I even saw the cushion go down. 
I muttered under my breathe leave me alone, just go away, and leave me alone and ran into my bedroom and locked the door.
I never mention this to my flat mates and yet immediately all the weird things stopped happening, a few days or so later we were in the upstairs flat having some drinks when one of the guys mentioned that "it" was back again. Apparently for ages things were always going missing or furniture getting moved around and so they'd got someone in the cleanse the place, a month or so previously and it had all stopped, but then the night before he'd come home to find his wardrobe in the middle of the bedroom.