network manager dosen't automatically launch while computer start-up

My system opensuse 11.4 64 bit KDE desktop.
Before yesterday ,the network manager always automatically launch while my computer start -up.It show a icon on system tray.And ,it pop up a window.That window’s title is “Networking Interface”,its content is “Auto eth0 activated”.
Yesterday ,it doesn’t automatically launch while computer start-up,but I can connect to the Internet normally.And ,there isn’t that system tray icon and pop-up window until I launch KNetworkManager from Kickoff Application Launcher.
Could any one tell me how to make Network Manager launch automatically while computer start-up? I am new to opensuse ,and new to Linux.
I am sorry my English is very poor.
Thanks for any response.