OK, things are spontaneously up and running again. The tech support people at TWCable said they would send someone out on Wednesday, but we're up and running so if things look smooth tomorrow I'll probably call and cancel the service call. It feels like it's a little bit sluggish; I checked a couple of bandwidth meters, and sure enough, I'm running somewhere between 150 and 350 Kbps right now, where I should probably be getting download speeds of 1.5 Mbps. Whatever. At least I'm online. Maybe it's just a high traffic time. I'll let the dust settle and check again in a couple of days...