I had an experience when I was home for x-mas while I was at UT (about '94) and it freaked me out. I told my Mom about it and she told me that it was a bad dream, though I knew it was not.
I woke up and heard someone talking to me from my closet, very calmly telling me he was going to kill me. I tried to scream out, but couldn't. I tried to move but couldn't.
I just wrote it off as a bad dream, though I knew it wasn't a dream.
Then about 5 years ago, I read a post on Hornfans about sleep paralysis. That had to be it. It was just as described by most articles about it. Not being able to move, with a sense of evil of someone/something in the room. It's happened once in my life and that's it.