Windows 8.1 install not working

[Saffran]

So apparently, I have access to PSO2 again, and I wanted to install it on my new machine.
The official sega install launches and downloads the latest launcher, tells me it's done, then I press the button and... windows 8.1 tells me that he cancelled the launch of pso2updater.
I have admin rights and gave all kinds of permission to folder access, made a root directory for PSO2 etc, but nothing works. I couldn't find anything remotely connected to my problem on the official Microsoft support pages, and the official PSO2 page doesn't even mention installation problems.

So... if anyone has a lead... I'm all ears.
But first, some sleep.

[Korazenn]

Did you try using PSO2 Tweaker instead of the pso2launcher.exe? SEGA's launcher can be unreliable at times on different setups. Try downloading and installing Tweaker to install the game through there instead because, even if you don't want to use the patches or need it CyberKitsune's proxy, it can still work as your launcher/updater/installer.

Also, the best location for the PSO2 directory to have on your computer is the default: "C:\Program Files (x86)\SEGA", which is where the 'PHANTASYSTARONLINE2' folder should be, if possible. If there is already a folder there called "pso2_bin", go ahead and have Tweaker perform the install. If not, make the pso2_bin folder, then perform the install through Tweaker.

[Saffran]

The problem seems to be that I have admin rights and am the owner of the drive, but I still "need admin rights" to perform any action on pso2uploader.exe (not on any other file in pso2_bin).
Deleting doesn't work either, even in safe mode.

Edit : Just to expand on this, this is a windows 8.1 specific problem, updating worked fine on my windows 7 machine (I had to abort it because it's too old and playing PSO2 on it would kill it).

Second (and probably last) edit:

Took a while but I figured it out.
I basically had to configure "properties"-> "security" for every file in pso2_bin to the same owner (either my profile or admins works). It may not work the usual way (some files refuse to change ownership) so you may have to whip up the secret admin account, but once you've manually set the files, you should be OK. Make sure the updated exe files do not change ownership though.

[Saffran]

This exact same problem has resurfaced and the solution I used (which worked like a charm until last week or two weeks ago) is now utterly useless.

I tried installing the tweaker, but it doesn't update PSO2. It launches the game and the game tells me I don't have the right version then shuts off.

Edit: I had to apply my solution between the moment the launcher says "I downloaded the latest version" and the moment it shuts off to get updater.exe working. I then had to reapply the same solution to all components (launcher, pre-doanload, download, updater) to get it to work.

I think I'm just going to e-mail SEGA...