I've met people with PTSD. I don't think anyone fully understands it, but the basics are that its a long term reaction to severe stress. The stress can be long term or a single traumatic incident. Soldiers and rape survivors are two of the groups who commonly experience it. I don't know that you ever get "cured", but there are medications and coping strategies that help for most people.
What do you like to do on a typical Friday night?