This story was sent to me by Bill, who gave me permission to post it on the Castle of Spirits page (Chanda Wright, President National Ghost Hunters Society).
Several years ago when I had a roommate, we both experienced the very same event at the same time without being aware that each other was hearing the same thing.
I was lying in bed, ready to go to sleep with my stereo on very low volume. He was in his bedroom with his girlfriend. They too, had a radio on. I heard what sounded like the door to the vestibule in the living room slam shut, then 4 or 5 footsteps, then nothing else. I muted the stereo, thinking that maybe it was just my roommate coming back from the sub shop up the street and that I hadn't heard him go out. A few seconds later I heard my roommate mute the stereo in his room which had also been on very low volume. I didn't hear anything after that.
The next morning I asked him about it, since I was certain that he had heard the same sounds when he muted his stereo. He described hearing the same door slam and footsteps, then nothing. Slamming the vestibule door was not uncommon coming into the house, in order that it shuts properly with the weatherstripping that surrounds it. Now, let me present a little history that points to one possible explanation of the sounds.
Roughly two years before this event, my uncle had lived in this house until one evening, suddenly, he experienced a massive brain anurism and died across the street while leaning over the fender of a car holding a flashlight for a neighbor who was working under the hood doing some repairs. My thoughts are, since my uncle died suddenly, his spirit didn't know he was dead. The sounds we heard were his spirit entering the front door, as if he was coming home as usual. He used to sleep in the living room on a fold out sofa, a few steps from the front door. Prior to that, my roommate had heard sounds on two other occasions, but none as distinctly recognizable as the front door and the footsteps. Since then, the sofa has been removed and the downstairs renovation has totally changed the environment of the living room. I didn't get rid of the sofa or start renovating because of the ghost, but I do believe that changing the 'familiar surroundings' of such a haunting will cause a spirit to move on.
When I shared this experience with another friend of mine, he offered an interesting twist that I hadn't previously considered. If it was the ghost of my late uncle, maybe he didn't like my roommate very much so he was making a ruckus.