First, it seems you are using an outdated version of the GSX installer, since the current version comes with the current version of SODE, which is 1.5.3.
Also, be sure you install the P3D V4 Hotfix 1, because it has fix a bug that resulted in no executables being loaded if your DLL.XML or EXE.XML (which we do not use anymore), was corrupted for any reason.
And of course, the usual suggestions of being sure you download and install with the antivirus disabled, and to configure the antivirus to exclude the Addon Manager folder from scanning before starting the sim.