Why won't the "To" box on Yahoo! "Create New Mail" no longer load?

It used to be that when I was writing an e-mail, I would start typing a name (of my contacts) in the "To" field. After the first, if not second letter, I got a drop down menu of all the people whose names begin with that letter. Then i clicked on the one I wanted.

NOW, I can type a whole name, and nothing happens. Yahoo! stopped recognizing ALL of my contacts. I still have the list, though. So, I re-entered all the names, categorizing them and everything....Friends, Businesses, etc. No matter how many times I write to the same person, it never recognizes the name...even tough it's in my address book! How can I get this feature BACK?

This happens on both Internet Explorer and Google Chrome alike.