Same here but noticed my IP had changed about 6:30am this am. Looking thru all of my settings I noticed I had DNS on my firewall machine had an adelphia number. Delete it and let it find a new one. I did that and service was restored. Working fine now. (actually slightly faster...not much but a little better)
Calling adelphia/comcast they still give the song and dance that my account is still in a transition stage. I called my buddy who is a networking guru, he had me change my DNS entries and viola, i'm up and running.
Thanks for the tip Sandman, this whole experience has provided me with some good networking notes. Wait this is the grumpy forum, ....
Get FIOS - Verizon fiber optics.. .. Unbelievably fast and no problems so far! It is not in all areas yet, but will be the big player in the future. Cheaper than the rest also. Probably jump in price tomorrow