When I start FSX, I get a message to say that there is a problem with the couatl.exe file and that it doesn't have a verified digital signature. The only option is to press 'OK' and FSX continues to load as normal.
I guess this is the main problem, and you are the first one ever rerporting something like this.
All our executables are digitally signed, as required by FSX. The whole point to digitally sign a file, is to ensure the has the same version the developer delivered, and it hasn't been corrupted, either by a bad download or by a virus or something.
So, if you are getting a message saying the file doesn't have a correct digital signature, it means it has been corrupted in some way, either by a bad download, or a virus on your machine.
You can verify the digital signature yourself, bu right-clicking the FSX\fsdreamteam\Couatl\Couatl.exe file, and select the "Digital Signature" tab.