This has been explained many times already: it's a known FSX bug that, the first time a module is trusted, it might cause FSX to crash or give that warning. Doesn't happen on all system, but it's something that can happen with every module that has just been trusted.
The solution is exactly the opposite of what FSX suggest:
- You have to authorize the module to run, even if it crashes.
- Try to run FSX again and, if still crashes, don't do anything, don't uninstall but, reboot Windows and try again. It will usually fix itself after a reboot.
You might also want to check your antivirus, because it might have mistakenly blocked the module. If this is the case, the best way is to:
1) Install with the antivirus entirely disabled
2) Configure the antivirus to ignore the FSX\bglmanx.dll file from scanning before launching FSX
