DISSOCIATIVE IDENTITY DISORDER (aka Multiple Personality Disorder)
All information found in the HAVOCA 
Dissociative Identity Disorder section was written by Jeff Vineburg (jeffv@op.net), I have taken extracts from his webpage to summarise the huge amount of information he has available. Sadly his pages are no longer available.
Good work Jeff and thanks for all the hard work you’ve put into this.
WHAT IS DISSOCIATIVE IDENTITY DISORDER?
The classic definition of dissociation is when you’re driving down the highway and you arrive at your destination, not totally sure how you got there (and you haven’t been drinking). You’re ok, but you don’t really remember driving the whole distance. Congratulations – you’ve just dissociated. We all do it to some degree.
DISSOCIATIVE IDENTITY DISORDER runs the gamut from the above to forgetting more things, to the opposite end of the spectrum – multiple personalities.
After discovering that something’s up with themselves, and the survivors will bear me out on this one, they might refer to themselves as freaks. Then they get to talking with other survivors and find out they say the same things about themselves! No, they are not freaks. They’re creative and resourceful, and they’re survivors.Dissociative Identity Disorder, formerly multiple personality disorder, is nothing more than a very creative coping mechanism. It is not an illness. They are not crazy. These people are survivors of all sorts of trauma in childhood, and it affects the way they process current information and react to everyday life.
Sometime early in life, generally before the age of eight, the patient suffered some severe, repeated trauma. This could have been physical, emotional, or sexual abuse (ritual, religious, incest, etc.). In uncommon cases, it can be a disaster that caused it.
While the abuse was taking place, it was too traumatic for the patient to take. So a natural defense mechanism became just simply `leaving.’ Other parts (alters/fragments) are created to take the pain of the abuse, as the `host’ (original personality) cannot bear it any longer. Or think of it as the ultimate denial – “that’s not happening to me” – so it happens to someone else.
This is why they won’t remember being abused. The patient actually doesn’t have knowledge of the abuse – someone else in the system took it for them. Typically, the host has no knowledge of what the alters did or sometimes they don’t know that the alters exist. Different trauma can create different alters. See – it’s a coping mechanism. It’s actually healthy.
[jbox]When I realized my girlfriend had dissociative identity disorder, I completely rejected the notion that she could’ve been abused as a child. My girlfriend – a victim of incest? Pshaw. Well, needless to say, I was wrong, with a capital W. Denial ain’t just a river in Egypt.[/jbox]