It's a bit annoying too how this error only seems to appear at the end of the process - It would be nice to see it at the start, and you don't get your hopes up.
That's because the installer must first install GSX, including *downloading* the very latest version of Couatl from the Live Update server, in order to be sure it has something meaningful to test (the version that has been *actually* installed).
In order to help users not posting the same question over and over (missing Couatl or GSX menus, due to Couatl not starting), Couatl now has a TEST mode, which is used by the installer to let you know in advance if there are problem in your system that are preventing it from starting.
Since 99% of the times, the reason is the antivirus, the message tells you that, but that not the ONLY reason, it's possible it might not start if you have a problem with VC++ libraries, which we obviously install but, in some cases just installing them is not enough to fix problems. See the "Addon Manager not showing up in P3Dv4 **SOLVED**" thread:
http://www.fsdreamteam.com/forum/index.php/topic,17484.msg122656.html#msg122656You can also try the Couatl test mode manually, by doing this:
- Open a command prompt ( Start->CMD->Enter ) and go to the Addon Manager\Couatl folder
- Type the following:
Couatl.exe --test
If there's a problem with missing system libraries, you might see some kind of error from Windows, saying something about it.