I'm trying out Linux Mint 12 on an AMD64 6-core with an MSI Twin Frozr (Nvidia Fermi - dual screen) card. I thought that I had finally avoided this problem with a re-installation but it's just started again.

When I start up using Gnome (w/special effects), I start to log in, the screen goes black and then comes back. I complete the log in with everything looking fine for a moment and all of the application icons in the upper right. The screen goes black again and comes back and the network app icon for opening connections is gone. In addition, the menu bar is now 1" high, and the app windows and dialog boxes all have a beveled look.

How do I get that network icon back? Or, how do you open a network or VPN connection without it?

Thanks for any help that you can provide.

I know this post is old but I had the same problem, so for future references, here is how I fixed it:

sudo vim /etc/NetworkManager/NetworkManager.conf

changed the line that says managed=false to read managed=true

restart the network manager

sudo service network-manager stop
sudo service network-manager start