This was the ONE scene that came to mind when I read the title of the thread.
Also, I believe it was Friday the 13th part II when the cat jumped in the window. Scares me every time LOL.
Also, in Signs...at the beginning when the dog barks at the little girl.
Also, the creepiness of the guy standing in the corner at the end of the Blair Witch Project was pretty weird.
Now, those are just "jumpy" scenes...but most disturbing/frightening I've seen is probably all 83 minutes of the original Texas Chainsaw Massacre. The grainy film, the memorable sounds (the steel door slamming shut), to the shear horrific subject matter. It could happen to anybody... (and to top it off, the opening text saying that it was based on true events...even though it really wasn't a true story).
Found nothing creepy about the Blair witch project other than how it managed to become so talked hyped