I'm at a loss, sorry. I never ran into any issues on mine (Windows 10) when I did a fresh install after they updated the installer on the website. Hopefully Axylus/someone else/ticket system will have a solution for you. In the meantime, you could try getting a working folder copy via a friend since the game does not need to be installed in order to be played.
Edit: A cursory Google search got me the following info and though granted the topic was for something else, the points still stand as certain AV have been known to flag the installer and the game. Also, since you mentioned your internet, if you happened to get the larger files on both tries, maybe they got corrupted somehow. Again, I'm just guessing at this point.
The error may come from different reasons:
- Corrupted or damaged file when it was downloaded.
- Installing a file saved in a network and not in the local computer.
- No Administrator rights in the computer account.
- Anti Virus blocking the installation.
- Windows Installer problem.
- A Registry Settings cause.
In the meantime you can also try running an online MD5 hash check on the files against the numbers mentioned in the website with the mirrors. At least this way you'll be able to verify the file integrity. If they don't match, then that particular file is corrupted.
Edited by NoDice, 26 April 2017 - 04:52 AM.