Ah alright I have P3D v3.4 so the newest, sorry for that 
That's what I needed to know, because another possible reason of modules not starting (assuming you are sure the antivirus is not a problem and you configured it to exclude the Addon Manager folder from scanning), could be a problem in one of your XML files (exe.xml and dll.xml), which (if corrupted) would prevent all executables from starting, even if they DO NOT use the dll/exe.xml files, like we now do in P3D 3.4 and above.
This was a bug of the sim itself, which was still present in the P3D V4 initial release, and was only fixed in the Hotfix (after our report, I must add...), so it's possible it might still there in 3.4.
The easiest way to check if your XML files are all ok, is to open them with Internet Explorer. If they are ok, they will open in IE, showing their structure properly. Otherwise, if they are corrupted, some text message will appear instead of the whole file.
The files are located here:
%APPDATA%\Lockheed Martin\Prepar3d v3\DLL.XML
%APPDATA%\Lockheed Martin\Prepar3d v3\EXE.XML
%PROGRAMDATA%\Lockheed Martin\Prepar3d v3\DLL.XML
%PROGRAMDATA%\Lockheed Martin\Prepar3d v3\EXE.XML
