by oj » Jun 26th, '13, 18:48
Are you using the tools in mcc? If so, see if it's set to allow the interface to be managed by networkmanager. You may have some conflict due to having the two tools trying to manage the connection. Networkmanager is the tool in the notification panel (bottom right) which, unfortunately, doesn't provide as much information as the mcc tool does. Nevertheless, you're probab ly better off using it, rather than the tools in mcc.
Aside from that, I find this situation is often fixed by restarting the wireless router. If that's an option I usually start with that to try to fix it.
Where I have not had access to the router (to restart it) I've had to reboot upwards of 3 times before the dang thing would get an IP. I've never figured out what the actual problem is.