Do you see the “Addon Manager” and the “GSX” menu under the “Addons” menu of the simulator ? If not, try this:
- Configure the antivirus to exclude the whole Add-on Manager folder from scanning.
- Try the Live Update again, or reinstall GSX using its most current installer, to be found under the "Products and Downloads" page of our site.
If that still doesn't work, the thread named "Addon Manager not showing up in P3Dv4 **SOLVED**" thread lists all the known solutions for missing menu entries from the "Addons" menu:
http://www.fsdreamteam.com/forum/index.php/topic,17484.msg122656.html#msg122656Even if the title says P3D4, the solutions are valid for FSX as well.