PROBLEM: This is the error I get when I simply try to open an email in Firefox. File not found Firefox can't find the file at http://us.mg1.mail.yahoo.com/dc/blank.html?bn=555&.intl=us&.lang=en-US. * Check the file name for capitalization or other typing errors. * Check to see if the file was moved, renamed or deleted. POSSIBLE SOLUTION: I contacted Yahoo and they had me clear (1) cookies and (2) cache. This did work so that I can now open the emails in Firefox. COMMENTS: Yahoo support said "Please rest assured that Yahoo! Mail is properly working as of this time. It would be best if you contact Mozilla Firefox help support. They have the right tools and knowledge with the settings to access Internet Sites like Yahoo! Mail on Mozilla Firefox browser." I'd like to know what to do to prevent this in the future because I've had this issue twice now in the last few weeks.