Have you tried using a different DNS server in case the one your ISP uses is hosed?
Yes, I did, but that's not it.
Actually I can reach all websites, just the response is only partially or extremely slow (and timing out). I know I'm not the only customer with that problem in my area, so I guess it's something bigger.
Will call them tomorrow
("which lights are on? .... have you tried power cycling your router? ...did you install anything on your computer?... by the way, we have an offer for a great upgrade for you" *yawn*)