Why were the ghosts so hostile to her?

Them and that grim reaper thing seemed especially nasty to her. The coffee shop scene with the woman (who presumably suicided) who left her hand print in the spilled sugar proved the ghosts could make contact with the physical world and even cause harm. It was not just psychological. It actually reminded me a lot of how the ghosts behaved in the movie the sixth sense.

Why was this? even the seemingly benevolent spirits like the little boy looking for his ''report card'' chased her down the hall. What was going on with this?