Sorry, but we really can't reproduce it, so it must something wrong on your system.
BTW, we have a new version online, if you run the scenery installer again now, it will be downloaded automatically. It might be worth trying.ì it.
I am also seeing this problem. If I allow couatl to run it crashes FSX.
Are you sure it's Couatl that is crashing FSX and not the Addon Manager (bglmanx.dll) ? Because, Couatl it's an external .EXE, which means it's quite difficult it might be able to crash FSX.