Unable to load any web page or FTP

When I open IE or Netscape on Win98 se I’m unable so load any web page at all. When I insist, IE or Netscape shuts down and I get an Illegal Operation error. On the other hand in a DOS prompt window, I CAN ping any web site using either the domain name or the IP address. Ftp doesn’t work either. This PC is able to log on the network and has no problem browsing the LAN. This is the only workstation that has this problem. Please help!!