'/sbin/ifconfig -a' returns:
lo Link encap:Local Loopback
Your system is not seeing your network cards. It is only seeing your loopback device.
I opened system->administration->network->edit->hardware device, and deleted the mac address from the box, and pressed Probe.
In less than 1 second it gave the correct mac address in the box.
Probe is not the reason your system has no network. What else did you change?