[ydl-gen] no internet access with YDL 4.0.1

[Albert]

I have the exact same problem in a PowerBook Ti 3.5
The network was working fine until one day I decided to switch off the 
airport, which I was not using, by unchecking (maybe unappropriate?) 
the checkbox for eth0 (airport) in the Network Settings GUI app. From 
then on I get the error that the ethernet card (for eth1) is not found 
and there's no way to get internet access from YDL.

Any help appreciated.