FSX Crash with ERROR news about the couatl.exe file.
Why you titled this thread about certain sceneries AFCAD, without indicating which sceneries and which AFCAD you are referring to ? If you are sure it's only happening with some sceneries, you should have provided with the relevant informations about them, otherwise it's not obviously possible for us to even *start* investigating it, let alone fix it,.
Have these problems always only by reinstalling the GSX and ADM can repair in time.
It's not possible this problem could be fixed by reinstalling, since the files are always the same and they surely don't "rot" overtime.
I guess the live update process is faulty.
No, it's not. If you think this is happening only on certain sceneries, it might be possible, but it cannot caused by the update, let alone fixed by reinstalling it.
How do I update this software without permanent problems?
Depending how old your last full installation or not, it might be enough to just follow the automatic update notifications, or not. But of course, this is always indicated in the Release Notes that you are offered to read before doing an update.
The last big update, which required downloading and installing the Full installer, happened Dec. 20th 2016, so you must start from this. After that one, we only had minor fixes which could be applied without exiting from the sim.
Please explain the entire installation process and the necessary system cleanup procedures.
It's not obviously possible to explain the entire installation process, but of course, it installs everything it needs for the software to operate correctly. If you want to do a clean install, you can reply YES to the questions "Do you want to remove the Addon Manager" and "Do you want to remove the Couatl scripting engine" which are made at the end of the Uninstaller.
If you want to do a MORE clean reinstall, you can remove all your personal preferences (so be careful, because this will remove all your airplane and airport customizations), by removing the following folders:
%PROGRAMDATA%\Virtuali\Couatl
%APPDATA%\Virtuali
THEN REINSTALL WITH THE FULL INSTALLER