Hi Dave,
Welcome to Special Families. Hopefully we can help here, if only to provide a place to chat and let off steam!
It is very dificult to give specific advice as obviously we do not know your particular circumstances or child but we will do our best! What kind of support do you get either from a CP related support group or a good paediatrician/doctor that you are able to discuss these issues with? I'm not an expert on Cerebral Palsy, but there can be a link between CP and challenging behaviour. There's a really useful fact sheet on the matter on the Scope website at
http://www.scope.org.uk/downloads/factsheets/word/challenging.doc. Organisations such as Cerebra can also be of great use.
We have recently have had issues with our own sons behaviour and have received help from several areas. A cognitive psychologist attached to our son's school has provided a good insight into his behaviour and he has recently referred us to a community behavioural psychologist and the behavioural nursing team. I do not know what services are around where you live but it might be worth finding out either through your G.P. or the school.
You say that you son is very intelligent and obviously has a talent on the computer! Might sound an off track question but have you ever discussed with a health professional the possibility that his behaviours could be to do with another condition eg. Aspergers? Our own son is 6 and is currently described as having "autistic tendencies" though no formal diagnosis. He, too, can get frustrated with certain situations and his behaviour deteriorated accordingly.
One thing which struck me when I read your post was the fact that your son is obviously very lucky and has been provided with a wonderful range of toys. However, all of these sound very sensory stimulating and I wonder if your son may be getting sensory overload. Our son has also got a Wii which he loves but for because he gets so into the games, he needs a cooling down period after playing with it just to regain his composure. Would it be worth trying a period of time without such stimulation and seeing whether your son calmed down a little bit? His liking for making things out of boxes might be his way of simplifying his play and bringing it down to a calmer level?
Lastly, I feel that it is very important that you and your wife devise a unified strategy to deal with your son's behaviour If there is tension however small between you then not only will your son pick up on this and utilise this to his best advantage, but obviously it is not good for everyone involved. If you both agree a system of behaviour modification such as the traffic light system, yellow/red card etc. and stick to it then there will be no discussion or tension as to the rights and wrongs of each situation as it appears. Similarly, it might be worth asking yourself why your wife runs around so much after your son. Has she fully come to terms with the situation or does she feel an element of guilt so is over compensating? I hope that you do not feel that I am speaking out of turn as I have already said I do not know your circumstances but on a general level and through conversations I have had with others, this can be the case although of course not always. Certainly through our experience, counselling has been of great use and even though I was cynical to begin with, I did feel it invaluable having someone else to talk to. You might find the following sites useful:
http://www.cafamily.org.uk/dads - site specifically for fathers
http://www.sibs.org - for issues regarding siblings
My son has just asked me what I am doing and I said that I was writing a letter to a Dad whose son was being a bit trixy. He just said "Say sorry, kiss, big cuddle" What more can I say - the best advice from a six year old!
All the best,
Paula