I don't have kids myself, and I don't really believe in "paranomal" things. But as a child, I did saw "ghost(s)" on many occasions. The images were vivid, I remember describing them to my grandma and other adults, though nobody believed in me.
I was also frightened by "them." One of the most vivid memories of ghost was when I was in preschool, probably 4 or 5 year old. I had a very bad bout of pneumonia, I was trembling violently, sweating a lot, vomitting and crying at the same time. My parents fed me some unknow medications, and my condition got worse. They rused me to the hospital, and I remember seeing ghosts when I was waiting in the emergency room, dehydrated, extremely exhausted, sick and weak in my mother's arm. I fell unconscious for some times. When I was conscious again, I tried to tell mom that I saw a ghost in the dark waiting to take me away the whole time she held me while I waited for treatment, and I begged mom not to leave me in the hospital. But I had to be hospitalized. And that "ghost" didn't take me away, afterall
I can't really explain those things. It's quite possible that it's just my vivid imagination combined with all the strange cartoon characters and stuffed toys that I had (and the mythological tales on tapes too :p).