Problems accessing Dag's site via yum

I'm having a very bizarre problem getting one of my systems to update
from Dag's repo.

I have a CentOS 4 server set up to access
http://apt.sw.be/redhat/el4/en/i386/dag/repodata/repomd.xml, the
standard URL for Dag's RHEL/CentOS 4 repository.

It gets a "Connection refused" error every time I try to run yum.

My other CentOS 4 servers can access apt.sw.be just fine.

On the affected server, elinks also fails to access apt.sw.be, but wget
works.

Access to other sites appears to work fine.

Changing the IP address did not help.  NAT'ing the affected server did
not help.  Disabling firewall rules did not help.

When the connection is refused, a packet sniff reveals that apt.sw.be
replies to the HTTP SYN request with a RST.  I'm not a TCP guru, but I
can't see any significant differences between the connection attempts
that succeed and the connection attempts that fail.  (The timestamp
value is different, and wget on the affected server apparently tries
twice to connect without seeint a RST; the second attempt succeeds.)

Any suggestions?

Josh Kelley