I did that but when I click on the SODE screen "X" I receive a "Runtime error". The error details is as follows:
Runtime Error (at 150:2448):
error on line 8: In a XML file only are permitted higher level elements.
This means your XML files were ALREADY corrupted before installing GSX, most likely because you have edited it by hand, or a bugged installer for another product corrupted them.
Our installer won't dare to touch an already corrupted XML file, risking to mess it up even further, so it notifies you of the error and abort, so you have a chance to fix it.
See here for an example of a problem which might be similar:
http://www.fsdreamteam.com/forum/index.php/topic,11252.msg88979.html#msg88979If that doesn't apply to you, and you can't figure out the problem, if you attach the files here (do not post the text, ZIP the files and attach them to a message), I can tell you.
P3D has two locations for the XML files:
%APPDATA%\Lockheed Martin\Prepar3D V3
%PROGRAMDATA%\Lockheed Martin\Prepar3D V3
You must check both of them.