I don't know what the problem might be. That error message sometimes pops out only the first time FSX trusts a new module, but it disappears on subsequent launches, if you simply ignore it, and exit from FSX, on the first launch. None has ever reported the problem like you are, with FSX not responding.
I'm sorry, but I can't reproduce it, either something is wrong with your system config, or there's another addon in conflict, or your antivirus is interfering. You can try to exclude the FSX folder from scanning in this case.
