[dmfdmf]

The brain lock is probably a bigger deal in your mind than in the mind of the interviewer. You seem to be framing the interview as a confrontation or holding perfection as your standard. The truth is that interviewers are often on your side and want you to do well, they need a good employee afterall. If you stumble just admit it with an honest comment like "Hmmm, I'm a little nervous." Unless the interviewer is a sociopath he will probably provide some guidance or try to break the tension with banter or something like that. Finally, practice makes perfect so take any interviews you can get even with companies or jobs that you aren't that interested in (this will reduce anxiety too since less is on the line) so you can get better at the process and do well when you find the job that you really want. It is a lot like dating ;-)