That's happening sometimes. There is no trojan horse or virus in the package.
This happens because the patch is opening a port for the software. By launching the program is looking to a server in the internet normaly, but the patch is intercepting this to give you the key for full access.

Cool, an installer, only the game itself doesnt run on my system because my virusscanner detects a trojan horse... Any1 else have this problem?