I hate interviews, these days they seem to ask you the most curly questions. I think it's supposed to be based on the idea that past behaviour predicts future behaviour or something. I had one only a month ago for the job I just got (yay) and they asked me if I could recall a time when I had an idea which made a difference to my team's success. I had about a billion ideas in my head and do you think I could think of anything intelligent to say? I just sat there, until eventually the mgr asked if I would like him to move onto the next question! I think I must have looked ridiculously relieved, and horribly embarrassed at the same time. The other difficult one was "Tell me about an instance when you were unsuccessful in contributing to your team's goal?" I blundered my way thru that one, but felt it was a pretty unfair question, like the one you were asked bee.
Threeangels, I know exactly what you mean - I did the same thing when I was about 20 and sabotaged my chances at an interview. It was for a paralegal job in the city, and I really wanted it. I was wanting to leave my job in the country and was bored with banking. The interviewer asked me why I wanted to leave the job I was currently doing, and after a few tentative starts she ended up pushing it further and I heard myself saying something about "stress" ie not liking it...I saw her face freeze and knew it was all over.
The worst faults question is a tricky one, but as most people have said as long as you show that you recognise your weaknesses and have taken steps to rectify them, you usually come out okay. Trying to pass off something positive as a fault like "I'm a perfectionist" usually sounds like your trying to cover up anyway!