We probably found the problem, and your report seems to confirm it.
You can install GSX in any drive but, the root folder you choose, should NOT contain the "GSX" name in it!
Yes, it's not supposed to happen, and we'll surely fix this, but it does happen, and I think you'll solve the issue by Uninstalling ( and reply YES to the question "Do you want to remove the Addon Manager ?", so you can choose a new folder next time ) and reinstalling in a folder that doesn't contain the GSX name in it.
F:\Tools in your case is perfectly fine, since it will result in installing everything under F:\Tools\Addon Manager