Networking Access

On a PC running Win98 SE, I have been having an odd problem with Networking. I noticed the problem when both IE 5 and Netscape 4.6 quit with illegal operations when visiting any web page. I also found that telnet, ftp and Windows networking were not able to connect to anything (but did not crash). I can ping other addresses. Removed and reinstalled networking components including TCP/IP. Updated NIC drives, tried a new NIC. Plugged into a different network port. Other PC’s do connect via these network ports. Any ideas what is up with this PC?