Okay there are many faults that could occur with the symptoms that you described
1.) Ensure that your BT socket box is connected properly, with no wires loose inside the box whatsoever!
2.) Your Modem is faulty, get a new one..I use a Speedtouch 330 which works fine with speeds up to 8meg and you can get it for around a fiver off ebay!!!
3.)AOL may of disconnected you from their service for numerous reasons or maybe their server is down!! Call them and see!!