Thanks in advance.  The solution is probably obvious, but not to me.  When I right-click the Voxpop Base.msi file and then click on "install" I receive this message: No VoxATC X installation found.  What am I doing wrong?  I'm running P3D v4.  I've tried placing the installation file in the VoxATC folder, but still no luck.  What am I doing wrong?

I don't use the VOXPop voices, but aren't you supposed to run the setup.exe file, not the .msi file? The setup file reads the Windows registry and finds the correct installation. It's also possible that the location of P3d4 in your Windows registry is messed up. It should be at:

HKEY_CURRENT_USER\Software\Lockheed Martin\Prepar3D v4\AppPath