I proceed to do the same thing, even resetting the router... no internets...
I try to go to a webpage, a diagnostic I've never seen before pops up (had BellSouth/ATT DSL since mid 2002), asking for username, password, email address. Type in the info. Takes me to another diagnostic page with a picture of the modem, and a set of instructions. I follow the instructions. Internets come back up... then down... then up... then down...etc.
I run a diagnostic ping tool that comes up. Gives an option to reset the Netopia modem to its original defaults. I click. Modem reboots. Everything now fine (for the time being anyway...).
I'd rather fark around with the equipment for a couple of hours than call AT&T support (although MOST of the time it IS on THEIR end!)... everytime I call support, I get some Indian named "Harold" that I can barely understand trying to talk me through eleventy billion proceedures to get the net back up. I REALLY hate that!