Comment 18 for bug 555571

I had this same issue after a reboot. Both wired and wireless were disabled in terminal.
yet only the wired network in /var/lib/NetworkManager/NetworkManager.state was disabled.

Ganton's post/link fixed it.

"I restarted my laptop because it could not be resumed: only a black screen with the shell cursor is shown on the top left."
"Network-manager-kde systray says that "network management disabled""
"This fixed my problem:
    service network-manager stop
    rm /var/lib/NetworkManager/NetworkManager.state
    service network-manager start
"