I just received my new D-Link USB wireless dongle to connect my Linux system to my wireless network...

I looked like it was detected as the device was flash and lsmod showed all sorts of USB entries as expected (with the correct device number, something like 2800.)

But the thing would not connect.

Looking at the log I had a message saying "networking is disabled by state file". This came from the Network Manager which was indeed disabled! Editing the following file:

/var/lib/NetworkManager.state

and changing the NetworkingEnabled variable from false to true made everything work! The manager was up and running now. I think I turned it off because my previous USB dongle (a Belkin device) would not connect on Linux.

Restarted my NetworkManager:

service network-manager restart

and everything worked like a charm.

Another problem that I resolved was my /etc/network/interface file. If that file includes names of interfaces that do not have a connection (i.e. no physical cable, the dongle is not connected...) then first of all the boot struggles for 2 minutes waiting for a connection. That was not the case before 11.10... Then the NetworkManager is likely going to be turned off (i.e. that flag I just talked about will be set to false for you!)

So... I checked my /etc/network/interface file and sure enough I had 3 entries: eth0, eth1, and eth2, all 3 not connected on that computer. Actually, the ehternet boards for eth2 and eth3 are not even present in that computer as far as I recall. I just comment out everything and now the boot is back to normal.