Why oh Why oh WHY??!!!!

Dear Good Lord will somenbody PLEASE tell my why my son will not stop headbutting things????
ARGH!
He headbutts when hes happy, mad, sad, bored and every other emotion and situation you can think of. We have stopped reacting to it and its definately abated somewhat. But if you tell him 'no', or growel at him he will headbutt the floor so hard it makes ya wince.
*sigh*
I know its quite normal for boys to go through the headbutting phase, but crikey I hope he outgrows it soon. Chris is having to build a wooden guard to go around the hearth of the fire place, because with winter coming up we cant continue to leave a protective blanket over it, and if we leave it uncovered Jason may actually kill himself the next time he headbutts it!!
Some people heave told us we should just leave it uncovered, and J will 'only do it once' - meaning headbutting the hearth. But the thing is he wont only do it once. I know my child and he will do it many many many times! And I dont want him to knock out all his teeth in the process....although it would help with the biting issue.... ;)
only kidding - the bitings pretty much under control now. its the hitting, scratching and headbutting we're working on now.
Oh - he sounds like a demon!!! Hes not - hes adorable. hes just a boy thats all ;)