As I've said, it's not possible the LSZH installer could cause this since installers are created automatically from a shared set of files so, apart from the scenery itself, the install, download and configure the sim using the same code.
Of course, before posting I double checked it, and ran the Zurich installer and, to be absolutely sure, I *downloaded* the installer from the website, instead of using my local copy.
And sure enough, everything works normally. I even tried uninstalling and reinstalling it twice, without installing anything else in between, and it works just fine.
The only logical explanation I can see why it doesn't work on your system, is that you antivirus might have flagged the Zurich installer *itself*, so it blocks Couatl.exe only when it gets installed by it.