Can't load 737 immersion textures (error message)

Installation Error: System.UnauthorizedAccessException: Access to the path 'C:\Program Files (x86)\Microsoft Games\Microsoft Flight Simulator X\gauges\FSFX\737\fsfx_RealEffects_1.dll' is denied.

   at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)

   at System.IO.File.InternalDelete(String path, Boolean checkHost)

   at System.IO.File.Delete(String path)

   at c.y()

   at VFXCentral.MainWindow.a(Object A_0, DoWorkEventArgs A_1)

   at System.ComponentModel.BackgroundWorker.OnDoWork(DoWorkEventArgs e)

   at System.ComponentModel.BackgroundWorker.WorkerThreadStart(Object argument)