Paul, likely your system is affected by Bug #1124803 "NetworkManager doesn't respond to SIGTERM in daemon mode"
You can check if this bug is related to your problem by the following commands sudo initctl status ureadahead-other sudo lsof | grep ureadahead
This issue assumes /var/log/upstart/ureadahead-other.log open for writing.
Paul, likely your system is affected by
Bug #1124803 "NetworkManager doesn't respond to SIGTERM in daemon mode"
You can check if this bug is related to your problem
by the following commands
sudo initctl status ureadahead-other
sudo lsof | grep ureadahead
This issue assumes /var/log/ upstart/ ureadahead- other.log
open for writing.