Frequently when I go to my Yahoo Mail (Classic) I can't open my inbox or any other box. If I close my browser (Firefox) and restart it seems to work

So when you click on inbox, or any other box, it simply does nothing?

Do you have to restart it every time you try to go there, or just the first time you visit, then when you restart it works as long as your computer stays on?

I've had issues of it taking it awhile to respond, maybe that's your issue?