Please clarify: are you saying you have the Couatl menu when FSX starts, but it disappears after a very short time ?
If yes, try to enable logging in the "Troubleshooting" section of the "GSX Settings" page when the menu is there ( start a default airport, if it disappears when you to to JFK ), exit from FSX, restart it, go to JFK and let it crash.
Then, check if a Couatl.LOG and a Couatl.ERR files have been created in your %APPDATA%\virtuali folder, and post them here.