This has been explained many times already: it's a known FSX bug that, the first time a module is trusted, it might cause FSX to crash or give that warning. Doesn't happen on all system, but it's something that can happen with every module that has just been trusted.
The solution is exactly the opposite of what FSX suggest:
- You have to authorize the module to run, even if it crashes.
- Try to run FSX again and, if still crashes, don't do anything, don't uninstall but, reboot Windows and try again. It will usually fix itself after a reboot.
You might also want to check your antivirus, because it might have mistakenly blocked the module. If this is the case, the best way is to:
- Uninstall the scenery. Reply YES when asked if you want to remove the Addon Manager and the Couatl Engine. Reply YES to both questions.
- TURN OFF your antivirus. Don't just exit from its interface, but turn off the real time protection. Actual wording changes between products, however, it's the option to scan every file that gets open in real time, without user intervention.
- Reinstall the scenery with the Antivirus TURNED OFF. Don't launch FSX yet.
- Configure the antivirus to exclude the following files from scanning:
YourFSXFolder\bglmanx.dll
YourFSXFolder\fsdreamteam\couatl.exe
YourFSXFolder it's usually C:\Program Files\Microsoft Games\Microsoft Flight Simulator X, if you installed it in the default folder.
- Now you can turn the antivirus back on, and launch FSX.
- Check you are seeing BOTH the "Addon Manager" menu AND the "Couatl powered products" menu under the "Addons" menu.
