network settings can't be changed

I'm using Ubuntu 8.04 dev release and I have had problems with network-manager GUI before (couldn't find the network.ui file) and I've been using wicd instead. Anyway, I decided to switch back to network-manager again (or to be honest, some updates removed my wicd so I couldn't access internet through wireless, although I can't do that now either). I ran into another weird problem. When I left click on network-manager tray icon and choose "Manual configuration..." (can also be done using $ sudo network-admin) it opens the usual network-manager GUI. Right, but everything is frozen (in grey colour) so I can't change any settings there. The scroll bars, tabs, and help and close buttons are exceptions.

Anyway, I found out something when I tried to launch network-admin on Terminal, check this out:

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$ sudo network-admin

** (network-admin:8652): WARNING **: Error doing GetSessionForUnixProcess on ConsoleKit: org.freedesktop.DBus.GLib.UnmappedError.CkManagerError.Code0: Unable to lookup session information for process '8652'

** (network-admin:8652): CRITICAL **: Unable to lookup session information for process '8652'
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Sorry if I missed something important, I'm really new to reporting bugs.