Internet Explorer “this page cannot…”

Running Windows98, PentiumIII: Internet connection through SBC – DSL with 2wire modem. Without warning, Internet Explorer can no longer open web pages. After troubleshooting with SBC and 2wire, we found that computer can ping the 2wire but cannot ping anything past the modem. 2wire thinks this is a communications problem (nic card) but am confused as to why it would be the computer’s communication problem if it can ping the modem. Also – dialup connection works but cannot access web pages through dial up either – can get into AOL service but cannot go out onto the Internet. Could there be a problem in the IE software?