Why do I get a page saying url not found on this server when trying to open email attachments?

I have old attachments that I have viewed many times. Now new or old will open.

Why do I get a page saying url not found on this server when trying to open email attachments?
Yahoo is still having some problems at the moment. Suggested cures range from Update Adobe Flash Player and Java script to clear IE7 cache, cookies, and browsing history. Different things seem to work for different people. It's causing attachments to not show, 999 errors where it won't let you do a particular action and some people cannot send receive delete or move mail. It's not just Vista either it's happening to some of us on XP. If all else fails go back to classic mail via this link. http://us.mg1.mail.yahoo.com/dc/optout?s... click yes when asked do you want to opt out. Hope this helps.