For those of you who have been unable to get VZ Nav to work because you're on a BES server and can't change the "permissions" to allow, THERE'S A NEW VZ NAV BUILD that works for those of us on a BES server!! (Version 2.9.8. Build 220). I have been having the same "green screen for 2-3 seconds" problem that everyone else has, until tonight. Here's what I did (assuming you already have 188.8.131.52 and have called VZW to have VZNav turned on).
DELETE any old version that you have on your device. Go to where you originally downloaded VZ Nav from (there is a link in your bookmarks, it was put there by VZW when you upgraded to .176). Download and install the new version. DO NOT set permissions during the install process.
The first time that you run the application, it will ask you if it's ok to change the permission settings. Assuming you agree, the program will automatically change them. You just have to save the changes, and also, you'll need to change the GPS setting again to allow for location based services.
All I can figure is that enough people were calling tech support to complain that they figured out a way to reset the permissions, regardless of IT policy.
IT WORKS!! (Of course, it's still $10/month, but for me, totally worth it).