I'd have to agree with I'm not joking sir. The first time I went through the interviews I flunked it on the tech interview because I was too rigid in my decision making. The interviewer will keep giving you extra information on the situation, some of it relevant, some of it not, apparently to see how you make your decisions. So if they give you information that would make you change your mind, go for it and just explain why, but don't change your mind just because you think that's what the interviewer wants to hear - sounds tricky, I know! Thats what I did this time round and I've just heard I've got through.
Good luck!