I reinstalled a video card that had stopped functioning. I opened the case, took out the card and reinserted it, stated the PC and now it tells my my copy of XP Pro isn't validated??? I have the original CD with COA and the number on the COA doesn't match the key in the machine?? How do I get revalidated and why did it change?? I installed the software last July with the COA on the label and it has run flawlessly since until this message that I may have a pirated copy???