Bizzare text box behaviour in word 2002

I have numerous text boxes on a page in one of my word documents, with a few of these when i change the text in one it changes the text in other ones at the same time but only a few. It would seem that they are in groups but there are only 2 or 3 of these groups all the rest don't have the problem, i looked in the help and it seemed to imply they were linked but i can't unlink them like it says so by using the 'unlink' button on the textbox toolbar. I have also tried deleting the 'linked' oneand creating a new one but the new one just seems to do exaclty the same. Any help or just a pointer would be appreciated, Iain