Since the update to the latest version that was recently released , Couatle is no longer visible in the addon's menu.
It's not entirely clear from your message, if the Couatl menu disappears while FSX is running, or it doesn't even start. If it doesn't even start, the most likely cause is the antivirus blocking it.
As explained, many times already, it's NOT enough to just install with the antivirus off, you MUST also configure it to exclude the following files from scanning:
I thought I was pretty clear and concise in my message. Furthermore I have configured my anti virus to exclude the above. It was my oversight not to mention that in the original thread; however it does seem I am not the only one experiencing this issue and a fix is needed. You don't have to be rude and arrogant because something has been explained already. I am not getting FSX crashes. A little respect to a paying customer wouldn't hurt either.