Confused about a dear friend of mine.

A really good friend of mine, we shall call her "Allison" is having memories of things that have never happened. She talks about how she saw her bestfriend kill herself, when she knows in real life that the person is still alive because she sees her everyday. She will be watching TV or talking to someone and all of the sudden just go into a daze, and say "Sorry, they were talking to me again." When i confront her about it she tells me that they are the voices of her friends that have died, and ghosts, which sounds really silly i know, but she refuses to accept hte fact that the people she says died are still alive. I have asked her to describe what happened the day her bestfriend died and she made ME cry because of the details. They were like it actually happened, she even drew like an outline of the place they were at. I dont know what is wrong with her and it is really stressful cause i dont know if she is being misdiagnossed. She was diagnosed with Mainc Depression, but I dont think thats right. From what I have told you does anyone think that they might know whats wrong with her?