coa labels

hey so i recently reinstalled xp onto my pc because I was having some problems. Anyways, now I can't activate windows, it says that my coa label is incorrect, which is impossible. Hp says that they can't help me w/out a huge fee because my warrenty ran out in august and microsoft says that I have to get in touch with Hp,:upset: i hate being bouced. So I would appreciate any help anyone could give me! ray: