Problem on TCP/IP

How can I put back the correct TCP/IP config on my win98 Internet Explorer & Outlook Express when an anti virus supplier asked me to uninstall then re-install the TCP/IP of my computer to accomodate their antivirus software & resovle their conflict / error? My computer could ping / trace route outside IP adresses of i.e. yahoo, hotmail & others but cannot send/receive on my outlook express & cannot surf the internet. Pls advise what’s wrong with it?
Thank you very much.