The addon <unkown> is causing couatl scripting engine to restart.
You don't have just that. You also have a prompt suggesting you to open the error log for details, which are needed to troubleshoot your problem. Please do that, and report the precise text of the error log.
If you missed or ignored the message in game, you can check the error log here:
%APPDATA%\Virtuali\Couatl.ERR