After several attempts to re-install Maple on one of my computers (and running into Error 40 at every step), I finally managed to install successfully. Turns out that the Nexon Downloader was having trouble delivering the client to my PC without corrupting the file. Someone on some forum (I can't recall which, I was searching all over the place last night) recommended installing FlashGet and downloading the Maple install package with that. I did so and started up the installer... and it went ahead without any error! So I wanted to post my experience here so that maybe others won't have to spend hours trying to get around Error 40.