The NDI.DLL file is one of Dialogic's system files, though I'm not entirely sure what function it serves.
You can try uninstalling and reinstalling just the Dialogic component (either through our setup or straight through their setup off CD #2 of the set), but if that doesn't work you've got some DLL or another (it may not actually be the NDI.DLL iteself) that's not in a happy state and isn't getting oveverwritten/uninstalled by the Dialogic setup.
The best I can suggest if that doesn't work is to wipe the box clean and reinstall, install on another box or try and get Dialogic involved (good luck on that one).
I have an Export/Import tool in use at a couple sites that can help capture all your users/handlers etc... so you don't have to reconfigure the box from the ground up if you want to try it here (assuming you end up having to wipe the slate clean).
Jeff Lindborg
Unity Product Architect
Active Voice
jlindborg@activevoice.com
http://members.home.net/jlindborg