I don't know if others have figured this out but I've read many posts on the web & email board already from people who are having the same trouble I did til I figured it out.
I don't know how to post the screen shot for this so I'll just have to explain it.
Under the Antivirus section: Privacy Control, open it up and go to the Advanced button. You will see a button to "Add site". Click that and put in the url without any odd characters such as // or : so the address I am on right now, I would put: forums.techguy.org and then click on Global Settings and User Settings to whatever you want to permit. I do everything BUT popup ads.
I have discovered that this works with yahoo, yahoo mail and almost any other site that Norton decides, for some odd reason, is against the rules THAT day. Once added, unless the sever address changes (and yahoo email does this sometimes) you shouldn't have any more problems with that site.
I hope this helps others. I ws ready to trash Norton 2004 before I figured this one out. Liz