Alright, since one word has caused a huge uproar, I've changed it. Happy now? I'm sorry if you took offense at it, but it had little to do with you. It is a matter for my players and me to resolve.
Now tell me the name of the player who played the sorceress.
Tell me the gender of the player.
Ah... you don't know. Interesting that, isn't it?
I guess my point is that while players may do things that have not been planned for and may not do the "smartest" thing at times, they shouldn't be made to feel "stupid" by either the DM or the other players. I play DND to have fun, not to feel like an idiot.
Well, unless they do act really, really stupidly, of course.

Fire Elementals are immune to fire. What would you do against a player who always attacked Fire Elementals with
fireball, regardless of what people told him or her about the Elemental's immunities, and what the DM was telling him or her?
There does come a point when you have to accept that you
have been stupid, and you'll be called on it. I don't think being constantly reminded of it is a good thing, however...
I think my campaign will move on from this occurence a lot easier than some of you seem to be able to. There will be consequences, yes, but those consequences will breed new adventures - which will be fun, and which are the point of D&D, surely? I'm not going to spend every session saying "You're a dumb player!"
Has this thread been pointless and without merit? Not at all - there's been a lot of interesting debate about railroading, about player actions and their consequences.
I don't run a campaign where the PCs get off if they make mistakes. There are consequences involved, which actually increase the enjoyment of the game. Would you enjoy a game where it didn't matter what you did, the DM would always fudge it so you won?
Cheers!