Hello, it is not sure whether you face this problem in front of delegates or in office or when you meet new people or while taking in a public place. If so you don't have any organic problem. You are just anxious or afraid or just phobia. You need to practice, practice, practice regarding overcome your fear. If the problem happens while taking to friends or with family members then you need to be asked few questions like any problem in naming, reputation, understanding what others tell or whether you are using neologisms in this case consult a neurologist. If you are just afraid consult a psychiatrist for behavioural therapy.