Blunt and I both have bought and payed for our BF2's, we got our CD Keys a bit mixed up but he now has his and works fine but neither will let my BF2 online. Its Just says 'CD Key Invalid'.
Have I been fudged by the BF2 key gen and need to get a new CD Key?
Loads of info about this on Google. Try this one for starters:
http://forums.gameon.co.uk/showthread.php?t=17942
and here is the link to my google search:
http://www.google.co.uk/search?hl=en&q=bf2+CD+Key+Invalid&btnG=Google+Search