the problem is with yahoo....any time you see a 500 error on a webpage the error is with the server servering that webpage.
As 404 is the server didnt find it
403 the server denied you access to it
200 - you never see it, the server worked fine.
and 500, the server returned an error.
for more details of HTTP codes, review RFC 2616 http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html