Cannot rid computer of incorrect serial key

[NOTS]

I was reinstalling my copy of max 9 after an OS re install, and mis entered the product key, which it accepts up until activation. Upon realizing my mistake I reinstall Max to start from scratch, however it skips the step of entering the product key, and has retained the mis entered key I mistakenly entered. I assume there is a file somewhere that it is reading this from, but I can't figure it out for the life of me. Even after an uninstall and removing all files associated with Max, when I reinstall it still shows the wrong key I entered. How can I change that or delete the file where that information is being retained? Thank you so much for your help!

[TravisNave]

Did you also clear the registry?

For more information on the Autodesk KB Support article concerning the clean uninstall of Autodesk products, see this link:

http://usa.autodesk.com/adsk/servlet/ps/dl/item?siteID=123112&id=2887771&linkID=9240617

[NOTS]

I really appreciate the response. I hadn't, however I followed the steps in the link you provided and the problem is persisting. I cannot imagine where that key is being retained. Short of re installing my OS, which is absolute last resort, is there any where else that information might be hiding?