Hi Virtuali!
seems I finally found the culprit
looks like "German Landmark X" does/has something which crashes couatl.exe when GSX is active.
I deactivated the GLX - layers in the scenery.cfg and everything runs ok.
I'll try to find what goes on and if there's a workaround
P.S. ...it looks as if it's about AFCADs with "non complete Airports" (e.g. Heliports with only landingspots and no parking) - I could recreate the same Problem with the Miami City Scenery by Drzewiecki Design (removing the Heliports fixed it) and Manhattan X from Aerosoft.
Maybe that helps.
Happy Landings
Juergen