I've changed no settings, I use the phone as dial-up (not cingulars connection manager), I've tried to setup connections on other computers using the same software and same drivers as I did when I set this up. It worked like a charm until that one chase day.
I've tried both wap.cingular, and isp.cingular...neither work.
From what I'm reading in cellular forums, they are really cracking down on the tethering now. They can monitor it, and they can block it, it's as simple as that. All I'm saying is be careful.