Same problem here. Yahoo can't help. It is a Safari problem. I have been unable to access Yahoo, my bank account, etc since doing Apple's update to Safari 3.2.1 Hopefully somebody at Apple will address this.
I also couldn't complete an Amazon transaction--two pages just kept recycling. I booted up Foxfire, and completed it with no problem. I couldn't even access this site--kept getting a note that Safari couldn't find the server. Still waiting for Apple to get back with some ideas.