Activation issue

For some reason when trying to start the game, it's started asking me for my product key to activate it. I downloaded the game through Steam and have been playing it with no problems since release, and all of a sudden this has popped up.

When I try and use my Steam key it tells me it's already active (obviously as I've used it) and so won't accept it.

Anyone know how to sort this? I'll try to reinstall but I'm not sure how to do that through Steam.

Hav you tried what's suggested here?

Thanks, just tried that - it all worked but I'm still being prompted to enter my product key (which still doesn't work).

Have you tried the key lookup url? Just in case you're entering the wrong activation key.

I'm copying and pasting off the one Steam gives me, so I don't think that's a problem.

Ah, I've no idea then. Maybe try asking in the thread I linked you to? If an SI staff member asks you to email him, he could sort out the problem for you.

All fixed - had to delete the C:/Program Data/Sports Interactive/Football Manager 2009 Certificate folder. The product key was then accepted.

Thanks for the help.