Just got Win 10 and it seems to be making yahoo mail messages under Firefox spin and spin and never open. I have to go back to the inbox and click on the message again, then it's there.
Have you tried a different browser - MS didn't put much into support for FF or Chrome - they want you to use their browser
I don't want to use Edge I don't like it and too invasive. Is there a way to make it load better in FF? Maybe it has something to do with AdBlock Plus? ABP works fine on all the other sites I visit so if that's the cause it's just on yahoo mail.