I've been having problems with Yahoo for about 12 weeks or maybe more now. I could always sign in OK but then it wouldn't let me read emails - sometimes it would let me read my Inbox, but not anything in a folder, sometimes nothing. And sometimes the screen would go black. It was as if the computer had crashed, but if I navigated away from Yahoo everything was fine.
There was a link to downgrade to 'Basic' setting, which I did, and everything is working fine now. The only 'extra' I miss is that I like the next email to be opened for reading if I delete the one I'm done with reading (so you can in essence just scroll through). I'm sure I used to be able to do that in Basic and I've told my setting that is what I want, but it ignores me - if I delete a read email it takes me back to the Inbox or Folder front list.
But at least I can read it.
I've been with Yahoo for about 20 years and never had this many problems. I doubt it is an area problem - I live in England, and people in the US are having the same issues, so the 'area' would be... worldwide? Also our weather has been OK (I'm not in one of the areas being hit by storms - and this started before all that did anyway).
I think it's Yahoo - they've futzed too much and broken it. I'll stay with them whilst my Basic still works - big hassle to move - but if that goes, so do I!!