Check your modem. Run diagnostics on the modem to see if it is installed properly and recognized. Check your phone line connection at both ends. If your modem doesn't find a dial tone on a good phone line the modem either isn't working properly or the phone line connection is a problem.
Diagnostics said the modem was working properly. Phone line connection is fine (used the same line I have for the desktop, which was working for that computer, but didn't work for the laptop). Even though diagnostics said modem is working fine, could it still be a modem problem?