Thank You,

It turns out that my problem had to do with the application's access permissions. These permissions are editable using dcomcnfg.exe. When I went into the default security settings and added the user that I wanted to be able to access the out-of-process COM server with, everything works.

Since it's not really an option for end users to change their dcom configuration, I decided to just remove access permissions checking for the application by setting the AuthenticationLevel registry entry for that application to 1. I added that value to the AppID key in HKEY_CLASSES_ROOT for that application.

-Mike