[Yum] yum mis-behaving

[Eli]

I'm seeing yum hang & choke on my systems.  Any clues as to why?  Anything I 
should experiment with?

Here is a common case:
[root at shield yum]# yum -d8 upgrade
Gathering header information file(s) from server(s)
Server: Fedora Core 1 - i386 - Base
CacheDir: /var/cache/yum/base
Getting header.info from server
failover: baseURL = http://fedora.redhat.com/releases/fedora-core-1
failover: path = /headers/header.info
[....sit here for a minute or two...]
headerinfofn: /var/cache/yum/base/header.info
Traceback (most recent call last):
  File "/usr/bin/yum", line 60, in ?
    yummain.main(sys.argv[1:])
  File "yummain.py", line 188, in main
  File "clientStuff.py", line 766, in get_package_info_from_servers
  File "clientStuff.py", line 103, in HeaderInfoNevralLoad
ValueError: unpack list of wrong size
[root at shield yum]# 

I also see it get stuck while downloading a package to upgrade.

TIA,

Eli Carter