I'm running Neorouter 1.6.3 on Mac OS 10.8 (Mountain Lion). I was using it on Snow Leopard before upgrading and haven't seen this problem.
You may have already done this, but try dragging the application to the trash, then reboot and re-install the latest version available on
http://www.neorouter/downloadsAlso, check that you're on the same version as your server.
The only issue I'm still having only occurs when I try to shut down NeoRouter... it always crashes on closing. Doesn't seem to affect anything and comes up fine next time I start it up. Ok, one other issue is that it pops up and says there's a newer 'pro' version available, but it is the same version and build that is already installed. No biggy.
Good luck,
Jeff