I've got some good and bad news here.
Originally Posted by dpm41
I finally installed 12.04 again and the 'device not ready' remained unchanged.
Once I typed the following command, NetworkManager was able to actually identify all three NIC:
I'm not too sure what have been causing this problem, but from what I could see is that the Network Manager MAY have been loaded before the kernel identifies the NIC!
sudo killall -9 NetworkManager
I'm not an expert, but it looks like killing the application AFTER booting the OS has fixed the issue.
Anybody care to clarify why this is happening? Is there a permanent solution given that the NIC work fine with 11.10?