Same problem here. Even if I delete the Coatl folder before start, as soon as I change aircrafts, GSX disppears from the menu and is not usable anymore.
This is known, every "normal" restart, which is any one that doesn't rebuild the cache, seems to not work ( for all affected users of course, I still cannot replicate it ) so, more than a problem of restarting, it seems a problem of loading the airport cache if it exists. I think if you start a session correctly, you can choose "Restart and rebuild cache" as many times you want, it will always work.
I still cannot replicate it but, I've seen it on an user system in a remote session. Assuming we cannot find the real reason, we might release a temporary fix ( tomorrow, since it's 00:55 here now ), that would always rebuild the cache, regardless of the restart, which would at least work as a temporary solution until we find the cause.