Utau Installer Issues (Error 2605)

[Blasphemy Incarnate]

I'll cut straight to the point, the UTAU installer doesn't finish the installation and instead throws an error before aborting.

• I have correctly applied the Japanese locale (and restarted).
  
• Confirmed I am using the correct decimal/comma separators.
  
• I have no previous installations of UTAU, run the installer as admin.
  
• Added the installer to an inbound rule for my firewall.
  
• Added full permissions for my user in the installer properties.
  
• Attempted changing the install location.
  
• Tried both 'install for this user only' and 'install for all users'.

I'd would be very grateful if anyone could assist in fixing the problem, installers on my pc never fail to vex me. I don't know any Japanese, but using a website to transcribe the error from an image roughly translated it to "An unexpected error was detected when installing this package. There may be a problem with the package. The error code is 2605."

In relation to the actual process; the installer runs, I use the default settings, the bar doesn't move for about a minute, it gets through about one and a half bars before raising the error message. Sorry for the long post, I wanted to give as much detail as I could so you wouldn't need to waste too much time ping-ponging questions at me. Huge thanks to anyone who might be able to help. (going to sleep for the next 7 hours btw)

Here are some images: