Firefox problem

I think my Mozila Firefox having problem loading my yahoo mail. Sometime it took for so long to loading my email and sometime the email I want to delete or read my email didn't happen. I don't know how to overcome this problem because I don't know how...

But the "loading" problem on yahoo mail didn't happened when I'm using internet explorer. Everything is fine. So what really happen here? Are these because of the internet connection or what? This is because before this I'm using TM Net streamyx connection the problem didn't happen. But when I'm using the P1 WiMax, the problem start to happen.

The thing that makes me feel very upset with this problem is "I can't open my yahoo mail using Mozila Firefox again". So in order to solve my problem, I'm using 2 web browsers: Mozila Firefox and Internet Explorer.