I installed 10.04 as soon as it was released and it worked right out of the box. But suddenly today the network manager refused to start.
Well, I could see the icon in the systray but it didn't show any network interfaces (I have eth0 and wlan0).
To get me an IP I had to run dhclient manually from the terminal which was successful. Finally I could google for help.
Google pointed me to this blog post where the author had run into the same problem.
Apparently there is a bug filed for this issue, I'm just too lazy to search in the bug database :)
Just wanted to share this with you if you bump into it.