I'd suggest thinking of the categories of questions you are likely to get, something along the lines of:
what kinds of work have I done before?what tidbits of technical know-how do I have in my brain?how do I use my brain when faced with a problem?how do I behave in a team?what is it I want from my career?what kinds of know-how do I think employers are looking for but I'm safer just admitting I know very little about? I think a part of freezing is fear of the unknown. Do your homework on the subject closest to you - yourself - in order to reduce the unknown. Maybe you'll still have interview questions you can't answer as effectively as you might hope, but you can improve the situation by reducing how frequently that happens. When you are confident about what you can answer, you may also find yourself more confident to say "gee, I have no idea how to answer that one - can I mull it over while we continue with other questions?". May not be the strongest answer, but could be an acceptable improvement over having a blank look on your face when an interviewer asks you a question that stumps you.

[ February 13, 2006: Message edited by: Reid M. Pinchback ]