The problem that still exists is that the GSX menu has disappeared overnight - without me doing anything.
There isn't any GSX menu, you mean the *Couatl* powered menu. But, as I've said, you also posted a screenshot of the "Couatl has generated an error" message and that IS generated by Couatl so, either you are seeing that error, so it means Couatl is running OR you are not seeing its menu, which means Couatl is NOT running, but then you shouldn't see the error either. Please, clarify your current situation.
provide step-by-step instructions on how to uninstall whatever is left of GSX and then to do a complete fresh install
This IS an entirely fresh install:
- DOWNLOAD AND INSTALL with the antivirus entirely OFF
- Uninstall GSX. 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 GSX 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\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