The bible does not say spirit of deceased are capable of wandering the earth to haunt people. As a matter of fact it says man is destined to die once and then face judgment so no one's spirit remain on earth nor do people reincarnate. I think paranormal activities may either be fake, hallucinations from mental illness or drugs, or demonic activities. Why are they not frequent if demonic in origin? God has the ultimate power and authority over everything therefore Satan and demons cannot do anything (i.e. influence nature or create havoc) without His permission. So I think it's God's protecting hand on us.