My ds (who is 8) appears to me to be over the top in his reaction to disappointment.
He will cry hysterically if something is not going the way he expects and them sometimes bang his hand into his head or bang his head into the wall. He does not seem to be doing it very hard but the fact that he does it all all worries me.
I am no longer sure if this is normal (being what appears to be overly upset) for his age or if this is an indication of a larger issue which needs to be addressed professionaly.
Have you voiced your concerns to your pediatrician? I agree with pp, this does sound like something that requires further investigation. Could be nothing out of the ordinary, but its always good to know.