Hope this isn't too much of a repost, I quickly tried looking but couldn't find anything.
I installed wicd and it removed knetworkmanager. Now my eth3 (the wired ethernet card, an nvidia which was working with knm before) is disabled. It doesn't show up in ifconfig.
When I go to the kubuntu Networks Settings, it shows that interface disabled. Enabling it via the button causes it to go green for a split second then become disabled again.
I suspected wicd was running and disabling it, so I removed that....but that didn't do anything.
Now I'm offline on that machine. Can someone point me to a more forceful way of enabling eth3?