That is something I was going to bring up on this topic...but I guess I don't have to now (ah, first-hand experience...no better teacher).
No matter how many 'safety features' are built into the system, things can still go horriblely, horriblely arry.
Best examples I can think of: 1) Star Trek: TMP
STARFLEET VOICE (shaken)
"Enterprise... what we got back, didn't live long. Fortunately."
(Ct.: http://www.dailyscript.com/scripts/startrek01.html )
and
2) Galaxy Quest:
JASON
Did I just hear that the animal turned inside out and then it exploded? Hello?
GWEN
Hold, please.
(Ct: http://scifiscripts.com/scripts/galaxyquest_trans.htm )