Great Grandparent's Farm House

My freshman year of high school, we moved to a new house that was previously owned by my great grandparents. Both had been deceased and the house had sat vacant for at least five years or so by the time we moved in. It was a smaller farm house. For about the first 6 months nothing happened, but during the summer before my sophomore year the first occurrence took place.

Since my mom had started working nights, I had my two best friends out who happened to be twin sisters. I slept on the floor and they both shared my bed. I slept all through the night and woke up normally the next day. The next morning, both girls on separate occasions told me how they each had woken up and noticed someone watching me as I slept. They both told me that they figured it was my mom so they each had fallen back asleep.

Well like I had said, my mom worked night so it clearly wasn't her. The front door was chained shut and we were the only ones in the house. To this day I still get chills thinking about it.

Another instance was my sophomore year. It was around 3 in the morning and I had school the next day. A vent leading to our basement is located right by my bed. All of a sudden I was woken up by the sound of a Buzz Lightyear Toy repeating "To infinity and beyond!" coming from the basement. Over and over. Annoyed, I had decided that something was probably pressed against it and making a button stick. I walked down to my basement and found the toy in the middle of the floor, maybe a good 10 ft from my young brothers toy chest. Unnerved, I threw the toy in the box and sprinted up the stairs.

The next occurrence has probably spooked me the most. This was during my junior year which was only a few months ago. My mom had been complaining of her music boxes going off and how uneasy it had made her feel. I figured she was being dramatic and didn't believe her so I had completely forgotten about it. One night, I was trying on my prom dress standing in my mom's room. After a few seconds of looking in the mirror, I heard one of my moms music boxes start to play. And in play I mean play, as if someone had fully wound the thing up. I looked around trying to find it but there were none in sight. Frightened I ran back to my room and waited for my mom to get home.

We believe it's our great grandparents' presence because no occurrences have been violent or harmful in any way. Any advice??