I seem to be having weird sound issues with other aircraft like the PMDG 747 and NGX that are generally resolvable with cycling the sound in FS but in the MD11 when I turn on the APU and press the APU air button should I hear the sound of the AC packs running in this airplane? There is no sound which may be normal.

You should be able to hear the packs. If you are having issues with all your aircraft then it's time to look at your soundcard and drivers.Regards

Strange, I had to move msvcr71.dll out of my main folder. Why was this in there? Well, I accidentally purchased the CS767 and could not get any cockpit sounds to work so someone on a forum somewhere said to download and put this file into the main FSX folder. This actually worked to get the sounds but it interfered with other airplanes. So I deleted it because it is better to have the PMDG stuff work properly obviously.