We've been down for a day -- the DSL failed. Bummer.
I finally got a simple enough network setup at my end so my ISP would talk to me. They required a single computer with a crossover cable plugged into the modem before they wanted to talk to me about line problems. I guess they get enough problems with people's home equipment. So, they finally decided that my computers were outputting ARP packets and they were responding to them but I was not receiving any of their packets. Time to call the DSL provider -- Qwest.
I've heard bad things about getting technical support from the phone companies, so, with trepidation, I phoned the tech support number. Pressed "2" to say I had DSL. Pressed "3" to say I was not using Quest as my ISP, Pressed "2" to say this was a new problem. And I was talking to an actual human!!!!! No waiting, no hassle. Wow!!! I explained that I'd talked to my ISP and they said to call Qwest. He typed for a second and said "yes, you do have a problem". "There is a tech on the way to fix it". One hour later the connection was running again.
So, there are a lot of terrible stories out there, but this is a good story about DSL and phone company technical support and it has a happy ending. And now I have connectivity so my life can go on.