Haven't tried restarting networkmanager; however: find rebooting system works.

syslog messages:

Jul 29 19:25:52 karmic NetworkManager: <info>  starting...
Jul 29 19:25:52 karmic NetworkManager: <info>  (eth0): new Ethernet device (driver: 'r8169')
Jul 29 19:25:52 karmic NetworkManager: <info>  (eth0): exported as /org/freedesktop/Hal/devices/net_00_01_2e_0e_4f_1d
Jul 29 19:25:52 karmic NetworkManager: <info>  (ttyS0): ignoring due to lack of mobile broadband capabilties
Jul 29 19:25:52 karmic NetworkManager: <info>  Trying to start the supplicant...
Jul 29 19:25:52 karmic NetworkManager: <info>  Trying to start the system settings daemon...
Jul 29 19:25:52 karmic NetworkManager: <info>  (eth0): carrier now ON (device state 1)
Jul 29 19:25:52 karmic nm-system-settings:    SCPlugin-Ifupdown: init!
Jul 29 19:25:52 karmic nm-system-settings:    SCPlugin-Ifupdown: update_system_hostname
Jul 29 19:25:52 karmic nm-system-settings:    SCPluginIfupdown: guessed connection type (eth0) = 802-3-ethernet
Jul 29 19:25:52 karmic avahi-daemon[2838]: Found user 'avahi' (UID 109) and group 'avahi' (GID 116).
Jul 29 19:25:52 karmic avahi-daemon[2838]: Successfully dropped root privileges.
Jul 29 19:25:52 karmic avahi-daemon[2838]: avahi-daemon 0.6.25 starting up.
Jul 29 19:25:52 karmic avahi-daemon[2838]: Successfully called chroot().
Jul 29 19:25:52 karmic avahi-daemon[2838]: Successfully dropped remaining capabilities.
Jul 29 19:25:52 karmic avahi-daemon[2838]: No service file found in /etc/avahi/services.
Jul 29 19:25:52 karmic avahi-daemon[2838]: Joining mDNS multicast group on interface eth0.IPv4 with address 192.168.0.107.
Jul 29 19:25:52 karmic avahi-daemon[2838]: New relevant interface eth0.IPv4 for mDNS.
Jul 29 19:25:52 karmic avahi-daemon[2838]: Network interface enumeration completed.
Jul 29 19:25:52 karmic avahi-daemon[2838]: Registering new address record for fe80::201:2eff:fe0e:4f1d on eth0.*.
Jul 29 19:25:52 karmic avahi-daemon[2838]: Registering new address record for 192.168.0.107 on eth0.IPv4.
Jul 29 19:25:52 karmic avahi-daemon[2838]: Registering HINFO record with values 'X86_64'/'LINUX'.
Jul 29 19:25:52 karmic nm-system-settings:    SCPlugin-Ifupdown: update_connection_setting_from_if_block: name:eth0, type:802-3-ethernet, autoconnect:0, id:Ifupdown (eth0), uuid: 681b428f-beaf-8932-0000-000000000000
Jul 29 19:25:52 karmic nm-system-settings:    SCPlugin-Ifupdown: autoconnect
Jul 29 19:25:52 karmic nm-system-settings:    SCPluginIfupdown: management mode: unmanaged
Jul 29 19:25:52 karmic nm-system-settings:    SCPlugin-Ifupdown: device added (udi: /org/freedesktop/Hal/devices/net_00_01_2e_0e_4f_1d, iface: eth0): well known
Jul 29 19:25:52 karmic nm-system-settings:    Ifupdown: get unmanaged devices count: 1
Jul 29 19:25:52 karmic nm-system-settings:    SCPlugin-Ifupdown: (27854176) ... get_connections.
Jul 29 19:25:52 karmic nm-system-settings:    SCPlugin-Ifupdown: (27854176) ... get_connections (managed=false): return empty list.
Jul 29 19:25:52 karmic nm-system-settings:    Ifupdown: get unmanaged devices count: 1
Jul 29 19:25:52 karmic nm-system-settings:    SCPlugin-Ifupdown: end _init.
Jul 29 19:25:52 karmic nm-system-settings: Loaded plugin ifupdown: (C) 2008 Canonical Ltd.  To report bugs please use the NetworkManager mailing list.
Jul 29 19:25:52 karmic nm-system-settings: Loaded plugin keyfile: (c) 2007 - 2008 Red Hat, Inc.  To report bugs please use the NetworkManager mailing list.
Jul 29 19:25:52 karmic NetworkManager: <info>  (eth0): now unmanaged