As discussed, so many times already, GSX CANNOT crash your sim.
You are mislead thinking this, because there's a KNOWN bug in the Simconnect menu that, sometimes, freezes the sim and, of course, it doesn't have anything to do with GSX, it can happen with another other application with a menu, and even with the default ATC menu.
This is supposed to have been fixed in 5.3 HF2. You just say you have 5.3 so, it's not clear if you installed the latest hotfix or not.