Comment 47 for bug 882817

> nm-dispatcher.action: Caught signal 15, shutting down
> Asked all remained processes to terminate.......failed

Right, this looks like a NetworkManager/upstart bug. I don't know what would cause nm-dispatcher.action to be run or not, but it looks like sendsigs is killing the NM subprocess, breaking the interface prematurely.

I don't see this problem here when shutting down, and I also have NFS shares mounted. What does your network configuration look like before shutdown? ('route -n' output)