When I check my mail a small box says loading at top of the screen but then nothing happens how do I stop it?

I can't send e-mail, compose or read unless I do it very quickly. But if I read an e-mail and then try to send it, it won't send or it sends without telling me or changing screens like it always used to.When I check my mail a small box says loading at top of the screen but then nothing happens how do I stop it?
Yahoo have done some work on the e-mail system. Routine maintainance and updates. If you are still having trouble (and some people are) try this link. http://help.yahoo.com/l/us/yahoo/mail/cl