However, the game runs just fine. Loads quick and runs fine. Even REX 4 Direct HD. All my add on aircraft run fine.
You don't need to have the correct registry keys to RUN the sim. But is needed by any installer, to know WHERE the sim is located.
It can't be the registry keys.
Yes, it is.
The error message states GSX is looking for FSX not P3D.
Because, as explained in the other thread too, if P3D is NOT FOUND (because its registry key is missing or pointing to the wrong folder ), the installer tries to look for FSX. If EVEN FSX is not found, because the FSX registry key is missing or FSX is really not installed, the installer tries to ASK YOU where FSX is.
I don't understand. P3D is installed in exactly the same folders, etc. I used L-M's built in installer.
Something changed your P3D registry keys AFTER you installed it. Most likely, the Migration Tool, which is something that might have caused this. It's either that, or you moved P3D after the installation. No other possible causes of the P3D registry keys not matching its installed folder.
As I've said in the other thread that I suggested to read, you should either:
1) Reinstall P3D to have its installer fixing the registry keys.
OR
2) Check your registry key for P3D, be sure is pointing to the folder P3D is installed into. Use the REGEDIT default utility, and go to:
HKEY_CURRENT_USER\Software\Lockheed Martin\Prepar3D v2\AppPath