Here in the UK a couple of days ago NTLworld broadband had a DNS server problem which too everything out for hours. Normally I would connect using 'eth0' and when I got fed up waiting for the broadband connection to get fixed (you must remember, I wasn't absolutely sure that it was broken) I plugged my old external (serial) modem back in and dialed up on Freeserve.

Although I had a PPP connection on the moden, Kmail and Mozilla still 'looked' at 'eth0' and I could not connect, until I did:-

ifconfig eth0 down

(I think!!!! I cannot do it now, or 'click' - silence....... no post!)

Check man ifconfig or ifconfig --help

Hope this helps, Stoo.....