A family of Microsoft word processing software products for creating web, email, and print documents.
Just because you want something, it doesn't meant that it is possible.Shooting the messenger is not going to change the answer. I have suggested methods that may minimise your problems. No one is forcing you to use them. However I will repeat that you cannot force users to run macros - even those that are run 'automatically'.
A macro solution of the type that you think you seek is covered at
http://www.word.mvps.org/FAQs/Customization/ProtectWord2000PlusHeader.htm but it will not stop users working around it. And if you have users who are prone to tampering with your systems, it is the users that need to be addressed rather than the provision of a disruptive and useless measure with will not have the desired result. - but then you don't want to hear that.