When loading a managed C++ assembly, you may receive the following exception: System.IO.FileNotFoundException: The specified module could not be found. (Exception from HRESULT: 0x8007007E) at System.Reflection.Assembly.nLoad(AssemblyName fileName...

Once you have an assembly loaded, you can use Assembly.GlobalAssemblyCache Property to determine if the assembly is loaded from GAC or not. I am surprised that not many people know about this property.