Haunted House

Some of you already know about our ghost, but for those of you who don't. We have a ghost in the house. Probably not, but it makes for a nice conversation piece. We know that if someone was murdered/died in the house it has to be divulged when it's being sold and nothing was ever told to us about that. But I guess our house could be built over an old cemetery or sacred Indian grounds.

Within the first few months after we moved in, our office light would randomly come on in the middle of the night. At first, we thought, we must have gone to sleep not realizing we left the light on, but the more it happened the more we became aware of the fact that we knew we turned it off before going to bed. Also, the stereo, in the same room, began turning on in the middle of the night, but not always with the light. The thing with the stereo is that it switches between the cds, it doesn't always play the same one.
This doesn't just happen in the middle of the night, but it does typically happen after 10 p.m. One afternoon I was checking my email and the light started going on and off, on and off. I looked over at the switch and it was still in the off position. I calmly asked Nathan to come in the room and the the fan started going through the low, medium and high positions. He grabbed the remote, the light can be operated by remote, and started choosing different settings and it would work, but would go back to doing what it wanted once he pushed the button. A week or so ago, in the afternoon, Nathan was on the computer and I was playing with the dog in the floor, when low and behold, a cd started in playing. It's a very weird feeling when music just all of a sudden starts playing, there is no noise of cds switching or the stereo turning on, just soft music. We also noticed 3 black finger prints to the left of the light switch (on the wall). We are not dirty people, so we don't think we would have put the prints there and the prints are at a weird angle, so whoever did it, would have had to turn their hand in an awkward position.
Our friend Jonathan was kind enough to get our mail while we were on vacation and knew about our "ghost". One evening he stopped by, it just happened to be Halloween, and the light was on. He didn't think we had left lights on, but he wasn't sure. So, he started to believe us about our visitor. This past Saturday we had friends over for dinner and games. When we were showing them around the house, we mentioned in passing about our ghost. Of course, the guys quickly began reasoning how if there is an electrical surge...more technical details...that would cause the stereo/light to come on. WELL, it was after 11p.m we were sitting in the dinning room playing a card game and all of the sudden the stereo starts playing a cd. Everyone just sat there and kind of looked at each other, not knowing what to do. We all laughed about it, but you could tell our friends started to get nervous. The good thing, our new friends don't think we are crazy! :)
I am just waiting on the day I walk in the office and there is a message typed out on the computer. If you have seen What Lies Beneath you know what I am talking about. Very freaky!
As for me and my sanity, I have to tell myself it's just an electrical glitch. And I am fine if this "thing" stays in the office and just wants to play with the light and stereo, but once it moves into our room and starts doing other things, the house is going on the market!