My Mac Mail client has suddenly stopped accessing my Yahoo mail POP account and I can't figure out why?

My Mac Mail on my laptop suddenly stopped functioning with my Yahoo mail account (my iPhone continues to work fine). I'm not getting any error messages, just an exclamation mark indicating something is wrong. I've searched Yahoo Mail help to see if the settings have changed (which doesn't really make sense because my phone has the same setting and still works) but found nothing. EXCEPT that in one place on Yahoo help, the incoming server listed as pop.mail.yahoo.com and then in another place it's listed as plus.pop.mail.yahoo.com (thanks yahoo). Same was true for the outgoing smpt servers (one had the plus and one didn't). I tried both, but neither setting fixed the problem. My Mail client is continuing to check all other email accounts fine. Yahoo doesn't seem to have anything officially describing the settings for Mac Mail like they do for Outlook, Outlook Express, Eudora, Netscape Communicator etc... Anyway, would love an answer...perhaps it's finally time to leave Yahoo?