I'm not sure if you've resolved your issue, but I've got a question for you. From your post, it shows that you've downloaded the service pack for Inventor Professional 10/MDT 2006 Locked version. Is this correct? If you've got Inventor Series, then it's a different service pack. Also there is a Locked and Unlocked version of each. I normally work with Inventor Pro and the first time I had to work with Series, I downloaded the Pro service pack and got the same error.