When i tell you i am not the only one :
You might not be the only one that already had a problem with the simulator, that for some reason happened to surface only after installing GSX, without this being CAUSED by GSX.
As I've said already, have you TRIED uninstalling GSX and replying YES to the question "Do you want to remove the Addon Manager ? If the sim is still not starting, you can be sure the thing preventing it to start is nothing that has anything to do with GSX, because that YES, will clear up EVERY trace of our software inside the simulator.