There could be a set of different things causing your problem. First do you have a firewall setup? Is it configured to allow AOL to access the internet and act as a server? Secondly, make sure the proper lights are lit on your modem, heres a list of lights that should be on with your specific modem:

A. 3Com Home Connect
-Ensure the Power LED is solid green.
-Ensure the Link Status LED is solid green.
-Ensure the Data Rate LED is illuminated.
-Ensure the Multi-function LED is illuminated.

B. Motorola Surfboard
-Ensure the Power LED is lit.
-Ensure the Receive LED is lit.
-Ensure the Send is lit.
-Ensure the Online LED is lit.
-Ensure the Link LED is lit.

C. RCA DCM225
-Ensure the Power LED is solid.
-Ensure the PC Link is flashing or solid.
-Ensure the Cable LED is solid.
-Ensure the Activity LED is flashing.
-Ensure the E-Mail LED is flashing.

D. Toshiba PCX1100U, 2200 & 2500
-Ensure the Power LED is lit.
-Ensure the Cable LED is lit.
-Ensure the PC LED is lit.
-Ensure the Test LED is not lit.

Also, if your modem has a rear LED make sure it is solid green.

If the power light is not lit, check the power supply. If the PC, link, and/or Ethernet LEDs are not lit check to make sure the wire from your cable modem to the computer is securely fit and plugged in, also make sure you have the right drivers for your modem or Ethernet card installed properly. If you have a Toshiba modem and the Test light is lit, your modem may be defective. If the Service or Cable light is not lit or is blinking you may have line problems, if so continue to the next topic, what to do if you suspect you have line problems.