I often feel that way and try to defuse it the best I can with humor. For example if I make a mistake or ask a stupid question I will jokingly say some thing like "excuse me but I'm mildly retarded.." and of course the response is always positive to that and they see I can laugh at myself. But inside it does bother me, but I won't show it. If you show it you will refuel that perception. By deflecting the situation with humor it distracts from the mistake and shows you know your only human, have a sense of humor and can laugh at yourself. Of course if this has never been your style you need to break in to it slowly. This usually works best for me. I find otherwise I get very tensed, anxious and defensive. Not to mention paranoid and depressed.