Invalid Product ID

When installing Windows XP Pro SP2, it is installing fine until it stops and tells me my cd-key is invalid. The cd-key isn't invalid as I still have the packaging in my room and have installed it once on my desktop.
I also tried my spare from MSDN (which I get from uni) cd-key which is also for Windows XP Pro SP2 and it also does not work.
I can't choose to use the telephone to validate because it doesnt get that far, it stops me while it is installing.
I have deleted and reinstalled a few times now and checked the product codes many times and got other people to look aswell.

What is going on?

EDIT: Forgot to mention that the first cd-key is OEM, the other one I'm not sure about, it's just the one from MSDN

 

You have to telephone to windows support to reactivate your key.

 

read above please

 

An OEM key can only be used once. It's invalid because it has already been used on your PC.
An MSDN key can be used 10 times but the MSDN key is for the retail version and won't work with an OEM CD. Use the MSDN CD that matches the key.