This afternoon I brought home a spare PIX firewall from work, configured it, and dropped it in in place of my firewall. Whaddaya know. Same off-again, on-again, off-again problem. The IPs it handled could access my other hosts just fine, but kept losing the ability to talk to Cox's local router. That sounded very much like IP address hijacking. I would be up when Cox's router had my firewall's MAC addresses in its ARP table (the table the tells a system which IP belongs to which other system on its local network). I'd go down when Cox's router picked up the interloper's MACs.
I called Cox's support line. Their East-coast operation isn't very big -- that in combination with my being a business customer, meant that I got through to a level 1 tech right away. He understood the problem, but was having trouble with his test gear. He said he'd escalate it and someone would call me back. Twenty minutes later a level 2 gal called me. We chewed the problem over for ten minutes or so on the phone, then she kicked it "upstairs". We rang-off agreeing that it looked like someone had glommed my assigned IPs.
About an hour later, she called back. Level 3 had traced the problem -- another customer had indeed configured his equipment with my IPs. They had left messages and told me that they would "take steps" if the other guy didn't put things right tomorrow. A few minutes later, the same tech called back: the other customer had called them. He was apparently very apologetic, owned up to his error, and told them he was driving back to the office to fix it. Now, there's some self-interest for him: whenever the IPs were working for me, they weren't for him. So, his service had been bouncing all day too. But, I am very pleased with Cox's response, and the other customer gets a nod too for wanting to put things right.
I so sincerely hope that no one buys Cox. I like them just the size they are.
10:16 PM - Mr. Sorry I Stole Your IP Addresses was apparently good at his word -- all is back to normal.