ViberMedia
Android Enthusiast
Exit button does not seem to work all the time, after shutting down sometimes it connects again. I think this might happen when it cannot send the "exit" signal to the Viber server, and than it connects again.
The "Exit" button has nothing to do with being connected to the internet or not. It's client only, and simply closes Viber itself on your Android (no confirmation from server needed).
Please remove Viber, and reinstall it from Market and see if the problem persists. Also - see if you can identify a specific pattern for this problem (otherwise I won't be able to repeat it here in the lab).