I can run the standalone. I have authorized and can choose GPO (mono) or (stereo) from add instrument within Digital Performer, as step 2 in the DP page on the Garritan site shows. (http://www.garritan.com/DP_GPO_tut.html) However instead of the expected GPO interface (the synth) showing up, I get a little blank white box. None of my other instruments are doing this. I can open the regular Kontakt player but I think that would cause me to lose some controller functions? Plus, it just should work and is very unusual to get the blank white instrument like this. I see no one else posting about the same problem. BTW- I'm on a PPC, not intel.
I have tried reinstalling the AU plug-in and trashing my DP AU cache. Whenever it rescans for the GPO plugin, it says everything's hunky dory. They (GPO mono and GPO stereo) look normal in the instrument list and in the bundles window.