There is not any fix because that creates yahoo mail problems but some the causes of Yahoo mail are quite common in the Yahoo mail.
2.Forgot Yahoo mail password.
3.Continuously getting spam emails.
4.Can’t forward Yahoo mail to Gmail.
5.The problem in changing Yahoo password.
More help related to Yahoo mail then you can read this http://www.yahoosupportnumber.net/blog/top-5-yahoo-mail-problems/