Have you noticed that Yahoo URLs have been screwed up in the past few days? News seems to work, but maps and other Yahoo services end up with 404, thanks to some URL being prepended. You can workaround it by removing the first part starting with "http:" to just before the second "http:". I figured this bug would get fixed within an hour or a day at the latest, but the bug is still there as I write this.
Update: This problem turned out to be my fault. For a while, I have blocked — by rerouting to echo back – most of the ad sites using the KazaaLite's hosts file which has a list of domain names known to be used to serve ad contents. Yahoo has decided to reroute requests through a domain in the filter list, resulting in 404. I removed rd.yahoo.com from the filter list and the problem went away.