These may sound like ridiculous questions, but paranormal events usually follow certain patterns:
How long have you owned your home? Are you the first owner? Do you have any children, specifically between the ages of 10 and 16? Have there been any recent deaths in the family?
There is a phenomenon called "shadow people" (don't laugh), which paranormal experts have separated from ghosts, hauntings, and poltergeists into its own separate category. Here is some info from Wikipedia, but the best source for this is a radio show called COAST TO COAST AM. If you want, I might be able to dig up an appropriate episode from the show's archives online:
"Shadow people (also known as Shadow men, shadow folk or shadow beings) are a purported supernatural phenomenon in which observers report seeing a dark form at the edge of their field of vision that disintegrates, or moves between walls, when noticed, usually within a split second.
Reports of shadow people are similar to purported ghost sightings, but differ in that shadow people are not reported as having human features, wearing modern/period clothing, or attempting to communicate. Witnesses also do not report the same feelings of being in the presence of something that 'was once human'.
Some individuals have described being menaced, chased, or (more rarely) attacked by shadow people (Some people see them with a weapon when attacked.); there have also been reports of shadow people appearing in front of witnesses or lingering for several seconds before disappearing. Typically, encounters are accompanied by a feeling of dread, although this may be simply distress of viewing such an event.
Most accounts of shadow people describe them as black humanoid silhouettes with no discernible mouths, noses, eyes, or any expression whatsoever, though purported witnesses have also described child-sized humanoids or shapeless masses. Some reports also include glowing red eyes. Generally, they are described as lacking mass, though their specific nature varies from a two-dimensional shadow to a vaporous or distorted three-dimensional form. Alleged images of shadow people have been posted on the internet, including one of a shadow person in a cemetery.
Their movement is often described as being very quick and disjointed; they may first move slowly, as if they were passing through a heavy liquid, and then rapidly "hop" to another part of a witness' surroundings. Some witnesses describe this movement as though the shadow entities they have seen "danced" from one wall to the next."
Wiki URL:
http://en.wikipedia.org/wiki/Shadow_people