Windows 7, unable to extract files
 

Won’t extract World.dat and many other files.

What specific error message do you get when trying?

Typically this will be because either the installed was not fully downloaded, or you're trying to install to a folder where you do not have write permissions.

So redownload the installer and try to install to a basic folder, like c:/OOTP20 and let me know if you still run into the same problem.