About rank reset and other errors.

Hello guys, Every time when I start up Call of duty modern warfare 2 I get this message : Your data is from an old version of the game.
You must reset ur rank to continue playing.

I rly need help, write if you know what to do.

Thanks.

you must re-install your game...put the cd in your pc again and press re-install in the .exe and after reinstall you are good.i had the same problem and i done that and now i am ok...NO UNISTALL ONLY RE-INSTALL...IF ITS WORKS THANK ME!!!!!!!!!!

Are you collecting 'thanks' or something?