I don't really have any ideas, but maybe you can look on the proper Clean Installer website now, since i'm guessing they have a FAQ page? The only other thing i can think of is are you the administrator , or just a guest, or a secondary account, on your computer? I don't know if this would be a problem, but it might be the reason?
did you install the .net thing that the website told you to go to? go to the help section download FAQs and look in downloading for fracking geniuses and go to the clean install link and read on the page, it will then redirect you to microsoft to download the program you need :D