OK, based on the list of packages provided by Scott Lewin, I uninstalled network-manager, network-manager-gnome and ubuntu-desktop (since ubuntu-desktop depends on network-manager) from my computer, rebooted and... the network interface is coming up fine!
i tried to reboot a second time, once more it worked OK. Then I reinstalled it and it doesn't work again.
So the problem comes from network-manager.
OK, based on the list of packages provided by Scott Lewin, I uninstalled network-manager, network- manager- gnome and ubuntu-desktop (since ubuntu-desktop depends on network-manager) from my computer, rebooted and... the network interface is coming up fine!
i tried to reboot a second time, once more it worked OK. Then I reinstalled it and it doesn't work again.
So the problem comes from network-manager.