It's not GSX that has "messed up" with key2mouse, the cause of this issue, and probably why your FSX crashes to desktop when you install any that comes with the Addon Manager, it's exactly the key2mouse installer.
This is something that was brought up a long time ago, key2mouse also uses the Esellerate library for its activation BUT it installs an older version of it, in the C:\Windows folder, which is correct for XP only (the version that comes with key2mouse is not Vista/Win7-aware), but is wrong for Vista/Win7, that require to use the current version, that works in the C:\ProgramData folder.
The issue is, the older version in the C:\Windows folder, takes precedence over the new version that we correctly install in the C:\ProgramData\Esellerate folder (if you run Vista or Win 7) and, even worse, our installer can't even remove it automatically, because to remove something from Windows, there's a special permission needed so, only you can do it, basically.
That's why you FSX is crashing, because the outdated .DLL which was put there by the key2mouse program, doesn't work with our products that requires the current one (which was release in *2007*), they crash when they access to it.
If you go in your C:\Windows folder, and you have an Esellerateengine.dll version 3.6.2.8 (the current one is 3.6.5.0), it's sure it has been put there by the key2mouse installer, if you just remove it, and maybe reinstall GSX, it's likely everything will work.
You will note Windows will ask an additional permission to remove it, which is why we can't do it from the installer.
