yum busted

[Greg Hamilton]

I seem to have broken yum. When I run 'yum upgrade' I get the following  
Python traceback.
I've included my yum.conf below. I've added freshrpms to it but I think  
it's otherwise original.
I don't know anything about how yum works. Does anybody have any clues?

Gathering package information from servers
Getting headers from: Yellow Dog Linux 3.0 base
Getting headers from: ayo.freshrpms.net freshrpms
Getting headers from: ayo.freshrpms.net ruffpack
Getting headers from: ayo.freshrpms.net updates
Getting headers from: Yellow Dog Linux 3.0 updates
Finding updated packages
Downloading needed headers
Finding obsoleted packages
Resolving dependencies
Traceback (most recent call last):
   File "/usr/bin/yum", line 44, in ?
     yummain.main(sys.argv[1:])
   File "yummain.py", line 202, in main
   File "nevral.py", line 263, in resolvedeps
   File "archwork.py", line 63, in bestarch
IndexError: list index out of range


/etc/yum.conf
[main]
cachedir=/var/cache/yum
debuglevel=2
logfile=/var/log/yum.log
pkgpolicy=newest

[base]
name=Yellow Dog Linux 3.0 base
baseurl=http://ftp.yellowdoglinux.com/pub/yellowdog/yum/3.0/RPMS.main/

[updates]
name=Yellow Dog Linux 3.0 updates
baseurl=http://ftp.yellowdoglinux.com/pub/yellowdog/yum/3.0/ 
RPMS.updates/

[freshrpms-updates]
name=ayo.freshrpms.net updates
baseurl=http://ayo.freshrpms.net/yellowdog/3.0/ppc/updates

[freshrpms-freshrpms]
name=ayo.freshrpms.net freshrpms
baseurl=http://ayo.freshrpms.net/yellowdog/3.0/ppc/freshrpms/

[freshrpms-ruffpack]
name=ayo.freshrpms.net ruffpack
baseurl=http://ayo.freshrpms.net/yellowdog/3.0/ppc/ruffpack/