Anyway, I had terrible things happen in meditation and did not realize this can happen till I read, "The Buddha Pill" which talks about people going psychotic in meditation. Stark, raving psychotic. One nurse took more than a decade to recover.
I've taken part in several very long, intense and even "extreme" Buddhist meditation retreats over the years. For me personally, it's been an amazing tool on so many different levels in my life. (Hasn't had any effect on ME or any of its symptoms, though!)
However, I just wanted to echo what you said, that it's not at all uncommon that people totally freak out, have psychotic episodes, have very severe bodily reactions etc -- I've seen it happen to people around me several times. It's really powerful stuff.
I believe that it's very important for everyone who practices meditation to be aware that this is something that can happen to anyone at any point in time. Not just to beginners or those considered to be "mentally unstable" -- it can happen to anyone, regardless.
Meditation teachers have a really big responsibility. They need to inform their students and also be able to take care of them if something like this should happen.