OK I got it yes when I close windows and restart then open FSX and ok GSX appears as Couatl. I hope I answered what you asked me...
Ok, so Couatl is clearly working on your system and, your only problem is that it doesn't work on a 2nd session.
If this is the case, then the problem might just be you are restarting FSX too quickly after the initial session.
As explained in some many threads in this forum, even if the FSX icon has disappeared, it doesn't mean it's safe to restart it, because all the executables started by it might still be finishing to close, and this will of course change depending how many you have and your system RAM ( which in FSX can't be more then 4GB anyway ).
AFTER a Windows restart, check with the Task manager if Couatl.exe closes normally when you quit FSX. Only THEN it's safe to start FSX again. If you restart it before it closed, it won't run on the 2nd session, becuase the first one is still closing.