This is a problem with the ne2k-pci driver, for which NetworkManager claims:
Feb 3 21:50:36 ubuntu NetworkManager: <information>^Ieth0: Driver 'ne2k-pci' does not support carrier detection. ^IYou must switch to it manually. A workaround is to not use NetworkManager and let ifupdown deal with the DHCP. This is done by having: auto eth0 iface eth0 inet dhcp lines in /etc/network/interfaces. ** Changed in: network-manager (Ubuntu) Sourcepackagename: network-manager => linux-source-2.6.20 Importance: Undecided => Medium Assignee: Simon Law => (unassigned) Status: Needs Info => Confirmed -- feisty fawn no network connection https://launchpad.net/bugs/82927 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs