I agree, it seems like a network problem at the mirror end. The
fact
that I had the problem occur on the FC4 host, with NO changes to that
host, and recover with NO changes to that host, makes me suspicious of
magic at the other end.
http://fedora.redhat.com/download/mirrors/fedora-core-rawhide
can you get to that url in a webbrowser?
-jef