Well. Probably an error when downloading the files, like a network disconnection at the exact time when it would screw everything up.
Try downloading it again.
Yeah, that's right.
Happened to me once too, my router didn't like me being online while downloading.......so I ended up with a not completely downloaded (aka corrupted file) myself.
Check your Internet connection (maybe your wifi connection) and try downloading again.
I personally only use Yuri's fixed installer, it's working for me like a breeze - perfectly fine.
To be honest without it I wouldn't be able to install the game at all, cause I'm one of those with a non English Windows.
But everyone as he/she prefers.
Good luck with downloading and installing the game and hope to see you around in the game soon!