If you happen to install Visual Studio, make sure you make no mistakes in your product key. If you don’t, it won’t tell you until after installing the multi-gigabyte beast. Then when you run it, you get an error. How do you re-enter the key? Simple, according to the knowledge base article you just remove and re-install the whole thing. 3 hours later, you’ll find out if you got it right or if you have to reinstall again.