I have had the same stereo for about 10 years and I did not have any issues with it until I moved into my new house (approx 3 1/2 years ago). My radio will turn on by itself and go to max volume. It happened 2-3 times a week until I unplugged it. Now I'm working long hours and I leave it on for my dog; if I foget to unplug it when I come home, it will turn back on (not every time but about a third of the time). I'm not operating any kind of remote control when this happens. I chalked it up to interference from a neighbor's remote, but recently I was dog sitting for my brother who lives in the country (nearest neighbor is about 1/2 miles away), and it happened with his radio the same way it happens with mine. About a week later, the radio in my car started changing in volume (I actually watched the numbers fluxuate). I have no buttons for volume on my steering wheel and was the only one in the car. It happened a few times, and the last time it happened I was able to record it on my phone. At one point in the video, I say "can you turn it up again?" and sure enough the volume goes up. I believe in the paranormal and prompted a "ghost" to change the volume, but I would really like a scientific explanation for this.

For the in home stereo or TV to turn on it usually takes a remote to do so. BUT the sun can act as a remote too. Sometimes as light passes through a given area and a reflection refracts the light to the electronic equiptment then it can cause it to turn on. Also sometimes spikes in the line can cause it to turn on or do any number of things. In a case like yours I would first try putting tape over the sensor and see if that does the trick. If not then I would try getting a good line filter and see if that does it. If not we do have a paranormal board here and your more then welcome to post there if you think that may be what is causing it after trying both of the suggestions.