Comment 2 for bug 92470

I cannot verify/confirm, however double check your /etc/network/interfaces file. KNetworkManager will not work properly if you have any special settings in this file. Here is a copy of my file that works like a charm.
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auto lo
iface lo inet loopback

auto eth0
iface eth0 inet dhcp

auto eth1
iface eth1 inet dhcp

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NOTE: I have also heard some people say that they experienced problems if they had anything except for 'lo' listed in the file.