I am using FF 4.0.1 version. For many years I've been using Yahoo mail and it worked great. Recently I created another Yahoo mail account for my wife and I have an access to it. From that time on, every time I try launching Yahoo Mail, it prompts me to login to her account, which I don't want. So, I have to click "Login as a different user" and re-enter my name and password. I tried just about everything: logging out, clearing cookies and cashe, re-logging in and out, etc. Sometimes it would let me login, but then on the next click (say, attempting to open a new email) it would try reverting back to her email login and I'd have to re-login again. Sometimes it gives me this error: Sorry, the page you were looking for could not be found Showing related results for: http://ucs.query.yahoo.com/v1/console/yql?q=select%20*%20from%20... This only happens in FF: using Yahoo Mail in IE or Opera is fine. That's why I feel it is FF issue, not Yahoo. And seems like it happens if I close FF and then open it again.