I got mine working using following steps..

1)I found what was causing my problem. /var/lib/NetworkManager/NetworkManager.state had NetworkingEnabled=false and WirelessEnabled=false. I don't know what caused this.

I deleted the file, rebooted, and now I can connect to my network again -- at least the wired network which I use at the office. I'll connecting to a wireless network when I get home.

2)Editing /var/lib/NetworkManager/NetworkManager.state setting NetworkingEnabled=true and then issuing "sudo restart network-manager" enabled networking again.