This happened to me to. NetworkManager died during the Interpid -> Jaunty upgrade. Flashplugin-nonfree is part of the upgrade. It needs to connect to adobe.com to download Flash, but cannot do so since NM is down. A reinstall will correctly download from Adobe.
I think this is only a symptom of another bug which kills NM during the upgrade.
This happened to me to. NetworkManager died during the Interpid -> Jaunty upgrade. Flashplugin-nonfree is part of the upgrade. It needs to connect to adobe.com to download Flash, but cannot do so since NM is down. A reinstall will correctly download from Adobe.
I think this is only a symptom of another bug which kills NM during the upgrade.