Ubuntu 8.10 NetworkManager(nm-applet) 無法執行- 解決方案

當由ubuntu 8.04升級到8.10(Intrepid)時，發現在面板上的NetworkManager applet不見了(NetworkManager applet is missing)
如果在Terminal執行nm-applet時，會出現下列的錯誤訊息

** (nm-applet:7559): WARNING **: applet_dbus_manager_start_service(): Could not acquire the NetworkManagerUserSettings service as it is already taken. Return: 3


(nm-applet:7559): GLib-GObject-CRITICAL **: g_object_unref: assertion `G_IS_OBJECT (object)' failed

解決方式如下：

• Fix nm-applet can't execute error
  

1. 修改/etc/dbus-1/system.d/NetworkManager.conf 和 /etc/dbus-1/system.d/nm-applet.conf
將下列紅色字，如果為deny，改allow
<policy context=default>
<allow own="org.freedesktop.NetworkManager"/>
<allow send_destination="org.freedesktop.NetworkManager"/>
<allow send_interface="org.freedesktop.NetworkManager"/>
</policy>

2. 重新啟動 dbus
sudo /etc/init.d/dbus restart

• Fix nm-applet "No connection defined" error
  

3. 停止 NetworkManager
sudo /etc/init.d/NetworkManager stop

4. 刪除 /etc/network/interfaces 或是更名(rename)
sudo rm /etc/network/interfaces

5. 重新啟動 NetworkManager
sudo /etc/init.d/NetworkManager start

6. 執行nm-applet

Reference:
https://bugs.launchpad.net/ubuntu/+source/network-manager-applet/+bug/249404
http://ubuntuforums.org/showthread.php?t=963335&page=3