Cannot seem to get rid of the color wheel only when I'm in Yahoo Mail

I have had my mac pro since January. For the first 3 or 4 weeks I had no issues. But ever since, I have experienced the color wheel only when I'm in my Yahoo mail account. The only way I can get rid of it is to force reload. But it quickly comes back after I open it up again. Sometimes I do this up to 15 times in 10 minutes. I've tried completely shutting everything down and it doesn't help. I've spoken to applecare and after about an hour on the phone the end solution they had was to quit Yahoo mail, stating you cannot use Yahoo mail with apple. However, I have an iPhone and it works without a problem. It's so frustrating.
Any ideas?

I'm with BT Yahoo Mail and I have problems from time to time with it but it's nothing for me to complain about. I get the spinning beach ball from time to time but I think it's just down to the server speed. I can open other sites when mail is having problems without any difficulty.

Could you clarify whether you are referring to checking a Yahoo mail account via Mail, or whether you're referring to checking a Yahoo mail account via a browser?

It happens with both for me Chas. Whether I use mail or Firefox or Safari, the speed at times is pathetic. I have just opened the machine up a couple of minutes ago and the speed is worse than dial-up. It must be a BT thing with me I think.

it happens when I'm in the browser through Safari.

A simple re-set of the Router solved my problem with this problem.

I will try it. Thanks. I have a feeling I'm going to be calling Apple care again.....