I had this problem a while back myself. I found the problem to be with WINXP updates and Norton updates. After service pack2 is installed and your norton programs auto updated install all new updates, if you do not go to the microsoft office page and download the new office update, wich you will need you serial number for, you will continue to have this problem. After the new update is installed, you will need to insert the office disk, and re-enter your serial number. After this you will not encounter this problem again, at least I have not any way. Hopefully this will help you. Good luck.
:wave: