Network Manager – Unmanaged Network Icon Issue

I was having problems connecting to the internet either by wireless or wired connection.
I keep getting an icon in the systray that has a tooltip that says "unmanaged" and when I click on it I get a "Network management disabled".

I googled and found the command:

sudo dhclient eth0

Which finally enabled my network and I have net. The problem is I still get the icon with the some word "unmanaged"

Can anyone help me out? I just want to know what is happening and why did I had to go to the command line to enable my network.

I had to put the computer in sleep mode and then it wouldn't wake up, so I rebooted the machine. The network manager problems started again, this time the file mentioned by maco had the value set to true and it still wouldn't work.

Anyone know how I can make this permanently work? I did a

sudo init 0

And when I booted the machine at a later time I had the network manager enabled.
Have no clue why.